Thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordinate bonds and preparation method thereof

Abstract

The invention relates to a thermoplastic polyurethane elastomer with multiple hydrogen bonds and metal coordination bonds and a preparation method thereof.The technical scheme of synergistic enhancement of multiple supramolecular effects is adopted, the multiple hydrogen bonds and the metal coordination bonds are sequentially introduced into TPU through a multi-step feeding method, firstly, polyether glycol or polyester glycol serving as a soft segment is subjected to dewatering operation, and then polyether glycol or polyester glycol serving as a soft segment is subjected to metal coordination bond modification; then adding isocyanate and a catalyst for prepolymerization; and after the prepolymerization is finished, adding hydrazide diamine capable of forming multiple hydrogen bonds for chain extension, then adding pyridine diamine capable of forming coordinate bonds for further chain extension to finish polymerization, finally adding a solution dissolved with metal ions into a reaction system for coordination, uniformly stirring and mixing, and volatilizing a solvent by a hot method to form a film. The thermoplastic polyurethane elastomer material simultaneously containing multiple hydrogen bonds and metal coordination bonds is obtained. According to the invention, integration of excellent mechanical properties and functionality of the thermoplastic polyurethane elastomer is realized, and diversified solution ideas are provided for reinforcement, toughening and functionalization of the thermoplastic polyurethane elastomer.

Description

Technical Field

[0001] This invention belongs to the field of thermoplastic polyurethane elastomers, specifically relating to thermoplastic polyurethane elastomers containing multiple hydrogen bonds and metal coordination bonds, and their preparation methods. Background Technology

[0002] Thermoplastic elastomers (TPEs) possess reversible supramolecular interactions such as hydrogen bonds, coordination bonds, π-π interactions, and cation-π interactions. These interactions can replace irreversible covalent bonds as physical crosslinking points, allowing for reconstruction under relatively mild conditions. Therefore, TPEs typically exhibit repairable and recyclable properties, extending material lifespan and aligning with sustainable development principles. Among various thermoplastic elastomers, thermoplastic polyurethane elastomers (TPUs) stand out with their abundant hydrogen bond sites, diverse synthetic raw materials, highly designable chain structures, and easily tunable microphase structures comprising both hard and soft phases, making them a widely studied research hotspot.

[0003] While the reversible supramolecular interactions in TPU endow it with repairability and recyclability, the generally weak nature of individual supramolecular interactions often results in low mechanical properties, making TPU unsuitable for applications requiring high mechanical strength. Therefore, rational molecular structure design is necessary to enhance and toughen TPU. Generally, increasing the number of supramolecular interaction sites in the TPU molecular chain or introducing stronger supramolecular interactions can increase the energy dissipation capacity of the elastomer skeleton, thereby achieving a synergistic improvement in strength and toughness. However, excessive or overly strong supramolecular interactions can restrict chain segment movement, leading to a decrease in elongation at break and a drop in glass transition temperature. T g Increased strength leads to decreased toughness and a narrower operating temperature range in TPU. Therefore, introducing appropriate supramolecular interactions into TPU is key to synergistically improving both strength and toughness.

[0004] Metal-metal coordination bonds are one of the most common supramolecular interactions. They are special dynamic covalent bonds formed by the combination of a ligand donating a lone pair of electrons and a transition metal ion donating an empty orbital. By changing the types of ligands and metal ions, coordination bonds of different strengths can be obtained, thereby achieving controllable adjustment of polymer properties. Furthermore, the introduction of metal-metal coordination bonds can also endow elastomer materials with different functionalities, such as shape memory, dielectric, and luminescence properties. Pyridine and its derivatives are common ligands. The nitrogen atom in the pyridine ring can react with many metal ions, such as Fe... 3+ Fe 2+ Zn 2+ Cu 2+ Cu + 、Tb 3+Coordinate bonds are formed. Therefore, modifying pyridine and its derivatives with amino, hydroxyl, and carboxyl groups can act as chain extenders to introduce the pyridine ring into TPU. Adding metal ions further facilitates the formation of coordinate bonds, improving overall mechanical properties. Furthermore, considering the production cost and market competitiveness of TPU, the selected pyridine derivative must be inexpensive, preferably a common commercial product or obtainable through a simple synthetic process.

[0005] Because the strength and toughness of polyurethane elastomers depend differently on the mobility of molecular chain segments, while supramolecular interactions between molecular chains are beneficial for strength enhancement, excessively strong forces can restrict chain segment movement, leading to a decrease in elongation at break and ultimately a reduction in toughness. Therefore, regulating supramolecular interactions in TPU to achieve a synergistic improvement in both strength and toughness is a key problem that this invention aims to solve. Summary of the Invention

[0006] To address the aforementioned issues, this invention employs a multi-supramolecular synergistic enhancement technique. A simple multi-step feeding method sequentially introduces multiple hydrogen bonds and coordination bonds into TPU. First, the polyether glycol or polyester glycol used as the soft segment undergoes dehydration. Then, isocyanate and a catalyst are added for prepolymerization. After prepolymerization, hydrazide diamine, which can form multiple hydrogen bonds, is added for chain extension. Next, pyridine diamine, which can form coordination bonds, is added for further chain extension to complete polymerization. Finally, a solution containing dissolved metal ions is added to the reaction system for coordination. After thorough mixing, the solvent is evaporated using a thermal method to form a film, resulting in a thermoplastic polyurethane elastomer material containing both multiple hydrogen bonds and metal coordination bonds.

[0007] First, the present invention provides a thermoplastic polyurethane elastomer comprising multiple hydrogen bonds and metal coordination bonds, wherein the polyurethane elastomer is formed by coordination of molecules represented by formula (I) with metal ions: (I), In formula (I), the molar fraction of residue A in compound B is 25%, the molar fraction of residue B in compound D is 50%, the molar fraction of residue D in compound D is 2.5%–20%, and the molar fraction of residue F in compound F is 22.5%–5%. A is a residue of a polyether glycol or polyester glycol compound; B is an isocyanate residue; D represents a residue of an acylhydrazide diamine compound; F represents a pyridine diamine residue; When compound A is a diamine, X = -NH-; when compound A is a diol, X = -O-. m is 0.1~0.8.

[0008] Furthermore, the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds contains metal ions that are cations of metals such as Cu, Fe, Zn, Mg, Ni, Mn or Co, and the molar ratio of the metal ions to compound F is 0.2~1.0:1.0.

[0009] Secondly, the present invention provides a method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, comprising the following steps: Step 1: Under inert gas protection, add compound A to the reactor, heat the reaction system to 80~150 ℃ under vacuum, and remove water under vacuum for 0.5~3 h; Step 2: Cool the reaction system to 50~80 ℃, add compound B and catalyst C in sequence, and stir the reaction for 1~4 hours; The molar ratio of compound A to compound B is 1.0:2.0~2.3; The amount of catalyst C used is 0.01 wt% to 1 wt% of the mass of compound A; Step 3: Cool the reaction system to 0~40 ℃, add compound D and solvent E in sequence, and continue stirring for 2~12 h; heat the reaction system to 60~80 ℃, add compound F and solvent G, and continue stirring for 12~48 h to obtain polyurethane solution H; The molar ratio of compound D, compound F and compound A is: x :(1- x ):1.0, where x The value range is 0.1 to 0.8; After adding solvent E and solvent G, the solid content of the entire reaction system is controlled at 10 wt%~30 wt%, and the mass ratio of solvent E to solvent G is 0.5~3.0:1.0; Step 4: Cool the polyurethane solution H to 20~40 ℃, add the solution of metal salt M in solvent J, and continue stirring for 2~6 h to obtain polyurethane solution K; The molar ratio of the metal salt M to the compound F is 0.2~1.0:1.0; The mass fraction of metal salt M in solvent J is controlled between 2 wt% and 20 wt%. Step 5: After filtering the polyurethane solution K, cast it into a mold and evaporate the solvent in a vacuum environment at 60~140 °C for 24~72 h; after the temperature drops to 20~35 °C, remove the film to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0010] Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, compound A is any one or a combination of the following compounds, and the chemical structural formula of compound A is: .

[0011] Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, compound B is any one or a combination of the following compounds, and the chemical structural formula of compound B is: .

[0012] Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, compound D is any one or a combination of the following compounds, and the chemical structural formula of compound D is: .

[0013] Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, compound F is any one or a combination of the following compounds, and the chemical structural formula of compound F is: .

[0014] Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, the catalyst C is any one or a combination of dibutyltin dilaurate, triethylamine, trimethylamine, triphenylamine, tripropylamine, N-methyldiethylamine, N-methyldipropylamine, N,N-dimethylethylamine, and N,N-dimethylpropylamine. Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, solvent E and solvent G are any one or a combination of tetrahydrofuran, dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and γ-butyrolactone; and solvent J is any one or a combination of chloroform, acetone, methyl ethyl ketone, dichloromethane, tetrahydrofuran, dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0015] Furthermore, in the method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds, the metal salt M is a hydrochloride, nitrate, or sulfate of Cu, Fe, Zn, Mg, Ni, Mn, or Co, or Ca(NO3)2· x H2O, CaCl2· xAny one or a combination of H2O, Zn(OTf)2, Tb(OTf)3, Cu(MeCN)4BF4. The beneficial effects of this invention are: This invention employs a design strategy that synergistically enhances TPU through multiple supramolecular interactions. It introduces multiple hydrogen bonds and metal coordination bonds into TPU while simultaneously regulating the microphase structure. This approach addresses the current technical challenge of achieving a balance between strength and toughness in TPU, while also endowing TPU with excellent repairability and recyclability, thus alleviating the environmental pressure on retired elastomer materials. The invention utilizes commercially available pyridine diamine and hydrazide diamine as chain extenders, providing ligands and multiple hydrogen bond sites, respectively. By controlling the molar ratio of the two chain extender diamines and the amount of metal ions added, the hard phase (coordination bonds and multiple hydrogen bonds) and soft phase (polyester polyols, polyether polyols) within the TPU skeleton are controllably adjusted, ultimately yielding a series of polyurethane elastomer materials with tunable strength and toughness. This invention employs two main methods. First, it selects diamine hydrazide as a chain extender, leveraging its high reactivity to promote the growth of TPU molecular weight. Simultaneously, the hydrazide moiety can form strong multiple hydrogen bonds with urea bonds, dissipating more energy during stretching. Second, it utilizes coordination bonds with higher bond energies as stable physical crosslinking points, preventing relative slippage of the molecular chains during stretching. The synergy between hydrogen bonds and coordination bonds further enhances the strength and toughness of the material. The TPU prepared by this invention simultaneously possesses high strength, high toughness, and a low glass transition temperature (TPU). T g It has puncture resistance and excellent shape memory properties. Attached Figure Description

[0016] Figure 1 This is a diagram of the polymer network structure of polyurethane coordinated with metal ions according to the present invention. Figure 2 (a) is a comparison of the mechanical properties of the polyurethane elastomers prepared in Examples 1, 2, and 3 with those reported in the literature, and (b) is a graph showing the key performance parameters of the polyurethane elastomers prepared in Examples 1, 2, and 3. Figure 3 These are photographs of the polyurethane elastomers containing multiple hydrogen bonds and coordination bonds prepared in Examples 4, 5, and 6. Figure 4 The thermal properties of polyurethane elastomers containing multiple hydrogen bonds and different coordination bond contents prepared in Examples 4, 5 and 6 are shown: (a) TGA curve, (b) curve of internal friction factor as a function of temperature. Figure 5 Small-angle X-ray scattering curves and atomic force microscopy (AFM) phase diagrams of polyurethane elastomers containing multiple hydrogen bonds and different coordination bond contents prepared in Examples 1, 2, and 3. Figure 6These are the stress-strain curves of polyurethane elastomers containing multiple hydrogen bonds and different coordination bond contents prepared in Examples 7, 8, and 9; Figure 7 These are the puncture resistance test curves of polyurethane elastomers containing multiple hydrogen bonds and different coordination bond contents prepared in Examples 7, 8, and 9; Figure 8 These are multiple shape memory curves of the polyurethane elastomer containing multiple hydrogen bonds and coordination bonds prepared in Example 10. Detailed Implementation

[0017] The present invention is described in detail through the following embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection of the present invention, and all compositions based on the core substances of the present invention as the main components are within the scope of protection of the present invention.

[0018] This invention uses the following technical route to prepare polyurethane:

[0019] The polyurethane polymer network structure prepared via the above route after coordination with metal ions is shown in [reference]. Figure 1 .

[0020] Comparative Example 1 According to similar preparation methods for TPU containing metal coordination bonds reported in the literature [ Polymer The preparation process, as shown in the following formula, is carried out according to the formula: [2022, 257,125266.]

[0021] In the comparative example, the mechanical properties of TPU were optimized by adjusting the amount of Cu(II) ions added, thereby controlling the number and strength of coordination bonds. However, the highly reactive hydrazide diamine capable of forming multiple hydrogen bonds was not introduced, resulting in lower overall mechanical properties of the final TPU: the tensile strength of the polyurethane elastomer coordinated with Cu(II) and pyridine N was less than 10 MPa, and the static toughness was less than 30 MJ / m. 3 (See [ Polymer , 2022, 257, 125266.]).

[0022] Example 1 The specific steps for preparing polyurethane elastomers containing multiple hydrogen bonds and metal coordination bonds are as follows: Under argon protection, 4.00 g of polytetrahydrofuran (PTF) was added to a three-necked flask. M n= 2000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 0.7533 g of isophthalic acid dimethyl isocyanate and 4 mg of dibutyltin dilaurate were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.1842 g of furan-2,5-dicarboxyhydrazide and 18 mL of N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.109 g of 2,6-diaminopyridine and 10 mL of N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed, the temperature was cooled to 25 °C, and 0.085 g of copper chloride dihydrate was dissolved in 24 mL of N,N-dimethylacetamide and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C. h; After the temperature drops to 20 °C, the film is removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0023] Example 2 Under argon protection, 3.00 g of polytetrahydrofuran (PTF) was added to a three-necked flask. M n = 1500 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 0.89 g of isophorone diisocyanate and 4 mg of N-methyldiethylamine were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.291 g of isophthalyl hydrazine and 28 mL of N,N-dimethylformamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.0762 g of 2,4,6-trimethyl-3,5-diaminopyridine and 10 mL of N,N-dimethylformamide were added, and the reaction was stirred for 48 h; after the reaction was completed and cooled to 25 °C, 0.021 g of copper chloride dihydrate was dissolved in 20 mL of acetone and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C for 60 h; after the temperature dropped to 20 °C... After being heated to °C, the film was removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0024] Example 3 Under argon protection, 2.00 g of polytetrahydrofuran (PTF) was added to a three-necked flask. M n= 1000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 1.0502 g of dicyclohexylmethane diisocyanate and 4 mg of N,N-dimethylethylamine were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.097 g of isophthalohydrazide and 18 mL of N,N-dimethylformamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.164 g of 2,6-diaminopyridine and 10 mL of N,N-dimethylformamide were added, and the reaction was stirred for 48 h; after the reaction was completed and cooled to 25 °C, 0.061 g of ferric chloride was dissolved in 10 mL of chloroform and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C for 60 h; after the temperature dropped to 20 °C... After being heated to °C, the film was removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0025] Example 4 Under argon protection, 4.00 g of polytetrahydrofuran (PTF) was added to a three-necked flask. M n = 2000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 1.0018 g of xylene diisocyanate and 4 mg of dibutyltin dilaurate were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.129 g of terephthalohydrazide and 10 mL of N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.1823 g of 2-ethyl-3,5-diaminopyridine and 20 mL of N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed, the temperature was cooled to 25 °C, and 0.045 g of anhydrous zinc chloride was dissolved in 20 mL of N,N-dimethylformamide and slowly added to the polymer solution, and the reaction was stirred for 4 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C. h; After the temperature drops to 25 °C, the film is removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0026] Example 5 Under argon protection, 6.00 g of polycaprolactone diol (PPD) was added to a three-necked flask. M n= 3000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 3 h; the three-necked flask was cooled to 80 °C, and 0.70 g toluene diisocyanate and 6 mg tripropylamine were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.291 g isophthalohydrazide and 30 mL N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.055 g 2,6-diaminopyridine and 10 mL N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed and cooled to 25 °C, 0.022 g copper chloride dihydrate was dissolved in 50 mL tetrahydrofuran and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C for 72 h; after the temperature dropped to 20 °C... After being heated to °C, the film was removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0027] Example 6 Under argon protection, 2.00 g of polycaprolactone diol (PPD) was added to a three-necked flask. M n = 1000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated under vacuum for 0.5 h; the three-necked flask was cooled to 80 °C, and 1.00 g of diphenylmethane diisocyanate and 0.002 g of dibutyltin dilaurate were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.194 g of isophthalohydrazide and 10 mL of N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.1392 g of 4-methoxy-2,6-diaminopyridine and 6 mL of N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed, the temperature was cooled to 25 °C, and 0.041 g of anhydrous ferric chloride was dissolved in 20 mL of methyl ethyl ketone and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C. h; After the temperature drops to 20 °C, the film is removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0028] Example 7 Under argon protection, 6.00 g of polytetrahydrofuran (PTF) was added to a three-necked flask. M n= 3000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 0.89 g of isophorone diisocyanate and 0.004 g of dibutyltin dilaurate were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.118 g of oxaloyl dihydrazine and 18 mL of N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.1392 g of 4-methoxy-3,5-diaminopyridine and 10 mL of N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed and cooled to 25 °C, 0.15 g of Cu(MeCN)4BF4 was dissolved in 20 mL of N-methylpyrrolidone and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C. h; After the temperature drops to 20 °C, the film is removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0029] Example 8 Under argon protection, 4.00 g of polycaprolactone diol (PPD) was added to a three-necked flask. M n = 2000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 1.05 g of dicyclohexylmethane diisocyanate and 0.004 g of triphenylamine were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.146 g of succinic dihydrazide and 28 mL of N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.109 g of 2,6-diaminopyridine and 10 mL of N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed and cooled to 25 °C, 0.041 g of anhydrous ferric chloride was dissolved in 40 mL of acetone and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C for 72 h; after the temperature dropped to 20 °C... After being heated to °C, the film was removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0030] Example 9 Under argon protection, 4.00 g of hydroxyl-terminated polydimethylsiloxane was added to a three-necked flask. M n= 2000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 1.05 g of dicyclohexylmethane diisocyanate and 0.004 g of N,N-dimethylpropylamine were added sequentially, and the reaction was stirred for 3 h; the reaction system was cooled to 40 °C, and 0.146 g of succinic dihydrazide and 18 mL of N,N-dimethylacetamide were added sequentially, and the reaction was stirred for 12 h; the reaction system was heated to 80 °C, and 0.1370 g of 3,4-dimethyl-2,6-diaminopyridine and 10 mL of N,N-dimethylacetamide were added, and the reaction was stirred for 48 h; after the reaction was completed, the temperature was cooled to 25 °C, and 0.081 g of anhydrous ferric chloride was dissolved in 30 mL of chloroform and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C. h; After the temperature drops to 20 °C, the film is removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0031] Example 10 Under argon protection, 4.00 g of polyethylene glycol (PEG) was added to a three-necked flask. M n = 2000 g / mol), the reaction system was heated to 120 °C under vacuum and dehydrated for 1 h; the three-necked flask was cooled to 80 °C, and 0.89 g of isophorone diisocyanate and 0.004 g of dibutyltin dilaurate were added sequentially, and the reaction was stirred for 2.5 h; the reaction system was cooled to 40 °C, and 0.232 g of adipate dihydrazide and 18 mL of N,N-dimethylformamide were added sequentially, and the reaction was stirred for 6 h; the reaction system was heated to 80 °C, and 0.109 g of 3,5-diaminopyridine and 10 mL of N,N-dimethylformamide were added, and the reaction was stirred for 36 h; after the reaction was completed, the temperature was cooled to 25 °C, and 0.043 g of copper chloride dihydrate was dissolved in 20 mL of N,N-dimethylformamide and slowly added to the polymer solution, and the reaction was stirred for 6 h; the polyurethane solution was filtered and cast into a mold, and the solvent was evaporated in a vacuum environment at 80 °C. h; After the temperature drops to 20 °C, the film is removed to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

[0032] Example 11 The properties of the polyurethane elastomers prepared in Examples 1, 2, and 3 were tested using a variety of techniques: polymer dynamic thermomechanical analysis (DMA) was performed using a DMA850 analyzer from TA Thermal Analysis, Inc., with a heating rate of 2 °C·min. -1The temperature range is -100 to 80 °C, and the frequency is 1 Hz. Mechanical properties were measured using a CMT4103 electronic universal tensile testing machine according to ASTM D882-88, with a clamping traction rate of 50 mm·min. -1 The tensile strength, tensile modulus, and elongation at break of the elastomer were tested separately, with each sample tested at least three times. The static toughness of the material is determined by stress (…). σ )-strain( ε The integral area under the curve is calculated using formula (1). (Formula 1) Thin-film puncture was determined using a CMT6503 electronic universal tensile testing machine, with clamp diameter... d = 3 cm, needle diameter D = 0.35 mm, compression rate is 50 mm·min -1 Small-angle X-ray scattering (SAXS) was measured using a Bruker NanoSTAR system with Cu-K-α as the X-ray source, at a wavelength of 1.5418 Å. Atomic force microscopy (AFM) phase diagrams were determined using a Bruker Dimension FastScan atomic force microscope in tapping mode. Shape memory was measured using a TA Thermal Analysis DMA850 analyzer, with a temperature range of -90 to 40 °C. The holding time for shape fixation was 10 min, and for shape recovery was 20 min. The test results are shown in Tables 1 and 2 below.

[0033] Table 1 compares the elastic mechanical properties of the polyurethane elastomers prepared in Examples 1, 2, and 3 of this invention with those of polyurethane reported in the literature. Figure 2 It can be found that the polyurethane elastomer prepared by the present invention has significant advantages in mechanical properties.

[0034] Table 1. Comparison of the elastic mechanical properties of polyurethane elastomers prepared in Examples 1, 2, and 3 of this invention with those of polyurethane elastomers reported in the literature.

[0035] Table 2 shows the key performance data of the polyurethane elastomers prepared in Examples 1, 2, and 3. It can be seen that the polyurethane elastomers prepared in this invention have good mechanical properties and puncture resistance, as well as a low glass transition temperature and good shape memory properties, resulting in excellent overall performance. Figure 5 A distinct scattering peak appeared in the 1D-SAXS curve, and a distinct dark-bright-dark structure also appeared in the AFM phase diagram, indicating that the polyurethane elastics prepared by Examples 1, 2, and 3 have a distinct microphase separation structure.

[0036] Table 2. Key performance data of polyurethane elastomers prepared in Examples 1, 2, and 3

[0037] Example 12 The thermal properties of the polyurethane elastomers prepared in Examples 4, 5, and 6 were tested and analyzed. Thermogravimetric analysis (TGA) was performed using a TGA2 thermal analyzer from Mettler Toledo, Switzerland, at a heating rate of 10 °C / min. -1 The temperature range was 30-800 °C under a nitrogen atmosphere; polymer dynamic thermomechanical analysis (DMA) was performed using a DMA850 analyzer from TA Thermal Analysis, Inc., USA, at a heating rate of 2 °C / min. -1 The temperature range was -100 to 80 °C, and the frequency was 1 Hz. As shown in Table 3, the thermal decomposition temperature of the polyurethane elastomers prepared in Examples 4, 5, and 6 was all higher than 295 °C, and the glass transition temperature was all lower than -50 °C, indicating that the polyurethane elastomers prepared in Examples 4, 5, and 6 had good thermal properties.

[0038] Table 3. Thermal performance data of polyurethane elastomers prepared in Examples 4, 5, and 6

[0039] Example 13 The mechanical properties of the polyurethane elastomers prepared in Examples 7, 8, and 9 were tested and analyzed. The mechanical properties were measured using a CMT4103 electronic universal tensile testing machine according to ASTM D882-88, with a clamping traction rate of 50 mm·min. -1 The tensile strength, tensile modulus, and elongation at break of the elastomer were tested separately, with each sample tested at least three times. The static toughness of the material is determined by stress (…). σ )-strain( ε The integral area under the curve is calculated, specifically according to formula (1); the membrane puncture is determined using a CMT6503 electronic universal tensile testing machine, with a clamp diameter of... d = 3 cm, needle diameter D = 0.35mm, compression rate is 50 mm·min -1 As shown in Table 4, the polyurethane elastomers prepared in Examples 7, 8, and 9 all exhibited good mechanical properties, and the films with a thickness of about 0.5 mm could withstand forces of more than 30 N, demonstrating good protective performance.

[0040] Table 4. Mechanical property data of polyurethane elastomers prepared in Examples 7, 8, and 9

[0041] Example 14 The shape memory properties of the polyurethane elastomer prepared in Example 10 were tested and analyzed using a DMA850 thermal analyzer from TA Thermal Analysis Company, USA. The temperature range was -90 to 40 °C. The holding time for shape fixation rate was 10 min, and the holding time for shape recovery rate was 20 min. As shown in Table 5, the polyurethane elastomer prepared in Example 10 can remember a programmed temporary shape at low temperature and recover its original shape after the temperature rises. After 5 shape memory cycle tests, its shape fixation rate and shape recovery rate were both higher than 98%, demonstrating excellent shape memory characteristics.

[0042] Table 5. Shape retention rate and recovery rate of the polyurethane elastomer prepared in Example 10 after 5 shape memory cycle tests.

[0043] In summary, to avoid the adverse effects of the relatively low reactivity of pyridine diamine (the pyridine ring has an electron-withdrawing structure) on the molecular weight of polyurethane prepolymers, this invention, through careful screening and performance optimization, creatively introduces a highly reactive hydrazide diamine as a chain extender. While ensuring the synergistic introduction of multiple hydrogen bonds and metal coordination bonds, this further increases the molecular weight. The preparation method described in the examples improves the mechanical properties of TPU to 65 MPa, the elongation at break to 800%, and the static toughness to over 200 MJ / m. 3 Furthermore, by adjusting the ratio of hydrazide diamine to pyridine diamine and the content and type of metal ions, the supramolecular interaction and microphase separation in the TPU skeleton can be controlled in multiple dimensions, ultimately enabling flexible adjustment of the strength and toughness of TPU within a wider range.

Claims

1. A thermoplastic polyurethane elastomer comprising multiple hydrogen bonds and metal coordination bonds, characterized in that, The polyurethane elastomer is formed by the coordination of molecules represented by formula (I) with metal ions: (I)， In formula (I), the molar fraction of residue A in compound B is 25%, the molar fraction of residue B in compound D is 50%, the molar fraction of residue D in compound D is 2.5%–20%, and the molar fraction of residue F in compound F is 22.5%–5%. A is a residue of a polyether glycol or polyester glycol compound; B is an isocyanate residue; D represents a residue of an acylhydrazide diamine compound; F represents a pyridine diamine residue; When compound A is a diamine, X = -NH-; when compound A is a diol, X = -O-. m is 0.1~0.

8.

2. The thermoplastic polyurethane elastomer comprising multiple hydrogen bonds and metal coordination bonds according to claim 1, characterized in that, The metal ion is a cation of metals Cu, Fe, Zn, Mg, Ni, Mn or Co, and the molar ratio of the metal ion to compound F is 0.2~1.0:1.

0.

3. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 1, characterized in that, Includes the following steps: Step 1: Under inert gas protection, add compound A to the reactor, heat the reaction system to 80~150 ℃ under vacuum, and remove water under vacuum for 0.5~3 h; Step 2: Cool the reaction system to 50~80 ℃, add compound B and catalyst C in sequence, and stir the reaction for 1~4 h; The molar ratio of compound A to compound B is 1.0:2.0~2.3; The amount of catalyst C used is 0.01 wt% to 1 wt% of the mass of compound A; Step 3: Cool the reaction system to 0~40 ℃, add compound D and solvent E in sequence, and continue stirring for 2~12 h; heat the reaction system to 60~80 ℃, add compound F and solvent G, and continue stirring for 12~48 h to obtain polyurethane solution H; The molar ratio of compound D, compound F and compound A is: x :(1- x ):1.0, where x The value range is 0.1 to 0.8; After adding solvent E and solvent G, the solid content of the entire reaction system is controlled at 10 wt%~30 wt%, and the mass ratio of solvent E to solvent G is 0.5~3.0:1.0; Step 4: Cool the polyurethane solution H to 20~40 ℃, add the solution of metal salt M in solvent J, and continue stirring for 2~6 h to obtain polyurethane solution K; The molar ratio of the metal salt M to the compound F is 0.2~1.0:1.0; The mass fraction of metal salt M in solvent J is controlled between 2 wt% and 20 wt%. Step 5: After filtering the polyurethane solution K, cast it into a mold and evaporate the solvent in a vacuum environment at 60~140 °C for 24~72 hours; after the temperature drops to 20~35 °C, remove the film to obtain a polyurethane elastomer film containing multiple hydrogen bonds and metal coordination bonds.

4. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, Compound A is any one or a combination of the following compounds, and the chemical structural formula of compound A is: 。 5. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, Compound B is any one or a combination of the following compounds, and the chemical structural formula of compound B is: 。 6. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, The compound D is any one or a combination of the following compounds, and the chemical structural formula of compound D is: 。 7. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, The compound F is any one of the following compounds or a combination thereof, and the chemical structural formula of compound F is: 。 8. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, The catalyst C is any one or a combination of dibutyltin dilaurate, triethylamine, trimethylamine, triphenylamine, tripropylamine, N-methyldiethylamine, N-methyldipropylamine, N,N-dimethylethylamine, and N,N-dimethylpropylamine.

9. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, Solvent E and solvent G are any one or a combination of tetrahydrofuran, dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and γ-butyrolactone; solvent J is any one or a combination of chloroform, acetone, methyl ethyl ketone, dichloromethane, tetrahydrofuran, dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

10. The method for preparing the thermoplastic polyurethane elastomer containing multiple hydrogen bonds and metal coordination bonds according to claim 3, characterized in that, The metal salt M is a hydrochloride, nitrate, or sulfate of Cu, Fe, Zn, Mg, Ni, Mn, or Co, or Ca(NO3)2· x H2O, CaCl2· x Any one or a combination of H2O, Zn(OTf)2, Tb(OTf)3, Cu(MeCN)4BF4.

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