Polyurethane elastomers and methods for making the same

Abstract

The application discloses a polyurethane elastomer and a preparation method thereof, and relates to the field of high polymer materials. At least part of molecular main chains in the polyurethane elastomer comprises a first molecular chain segment and a second molecular chain segment, and the molecular structures of the first molecular chain segment and the second molecular chain segment each independently comprise at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites, and the chemical structures of the first molecular chain segment and the second molecular chain segment are different. The polyurethane elastomer provided by the application has excellent toughness and stability.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and in particular to polyurethane elastomers and their preparation methods. Background Technology

[0002] Thermoplastic polyurethane elastomers combine the high elasticity of rubber with the excellent abrasion resistance, wear resistance, and reprocessing ability of polyurethane plastics, and are widely used in footwear, automotive industry, electronic products, and sporting goods.

[0003] Polyurethane elastomers typically consist of polyether or polyester soft segments and polyurethane hard segments, forming a microphase separation structure due to the thermodynamic differences between the soft and hard segments. The hard regions act as physical crosslinking points, reinforcing and promoting resilience. However, compared to traditional vulcanized rubber, thermoplastic polyurethane elastomers lack a stable covalent crosslinking network, resulting in significantly inferior stability, mechanical strength, toughness, and fatigue resistance. Therefore, supramolecular chemistry-based "sacrificial bond" strategies are often used to reinforce and toughen polyurethane elastomers, such as introducing non-covalent interactions like hydrogen bonds, dipole interactions, and coordination bonds. Upon deformation, these weak interactions break down first, absorbing energy.

[0004] However, due to the dynamic and reversible nature of non-covalent interactions, the non-covalent cross-linked network of polyurethane elastomers is easily damaged by external stimuli, such as high temperature, high humidity or other organic solvents, which greatly limits the use of polyurethane elastomers in some extreme environments. Summary of the Invention

[0005] In view of this, this application provides a polyurethane elastomer that has excellent toughness and stability.

[0006] The embodiments of this application are implemented as follows: This application provides a polyurethane elastomer in which at least a portion of the polyurethane molecular backbone includes a first molecular chain segment and a second molecular chain segment. The molecular structures of the first molecular chain segment and the second molecular chain segment each independently include at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites. The chemical structures of the first molecular chain segment and the second molecular chain segment are different.

[0007] Optionally, in some embodiments of this application, the hydrogen bond donor sites and hydrogen bond acceptor sites in the first molecular chain segment are the same; and / or

[0008] The hydrogen bond donor sites and hydrogen bond acceptor sites are the same in the second molecular chain segment.

[0009] Optionally, in some embodiments of this application, at least a portion of the polyurethane's molecular backbone structure is as follows:

[0010]

[0011] Where R1 represents the first molecular chain segment, R2 represents the second molecular chain segment, x and y represent the molar amounts of the first and second molecular chain segments, respectively, and the value of x ranges from 0.4 to 0.6, and y = 1 - x;

[0012] The chemical structure of R is: Where n is an integer between 20 and 30.

[0013] Optionally, in some embodiments of this application, either R1 or R2 includes a rigid group while the other includes only a flexible group. The rigid group is selected from one or more of an aromatic ring with 6 to 10 substituted or unsubstituted carbon atoms and an aliphatic ring with 6 to 10 substituted or unsubstituted carbon atoms. The flexible group is a hydrocarbon group with 2 to 5 substituted or unsubstituted carbon atoms.

[0014] Optionally, in some embodiments of this application, R1 and R2 are each independently selected from:

[0015] One or more of the following, where * represents a connection site.

[0016] Optionally, in some embodiments of this application, the first molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites, and the second molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites; or

[0017] The first molecular segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites, and the second molecular segment includes four hydrogen bond donor sites and four hydrogen bond acceptor sites; or

[0018] The first molecular segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites; or

[0019] The first molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites.

[0020] Accordingly, this application provides a method for preparing a polyurethane elastomer, comprising:

[0021] Provide polyurethane prepolymer, a first chain extender, and a second chain extender; and

[0022] Polyurethane is obtained by mixing polyurethane prepolymer, a first chain extender and a second chain extender and reacting them.

[0023] The molecular structures of the first chain extender and the second chain extender each independently include at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites.

[0024] Optionally, in some embodiments of this application, the method for preparing the first chain extender includes:

[0025] Provides a first reactant and a second reactant. The chemical structure of the first reactant is NH₂-R₃-OH, wherein R₃ is selected from one or more of an aromatic group with 6 to 10 substituted or unsubstituted carbon atoms and a hydrocarbon group with 2 to 5 substituted or unsubstituted carbon atoms; the chemical structure of the second reactant is... Where X is a halogen element; and

[0026] The first reactant and the second reactant are mixed to produce the first chain extender;

[0027] The preparation methods of the second chain extender include:

[0028] Provide a third reactant and a fourth reactant. The chemical structure of the third reactant is NH₂-R₄-OH, wherein R₄ is selected from one or more of an aromatic group with 6 to 10 substituted or unsubstituted carbon atoms and a hydrocarbon group with 2 to 5 substituted or unsubstituted carbon atoms; the chemical structure of the fourth reactant is... Where X is a halogen element; and

[0029] The third reactant and the fourth reactant are mixed to produce the second chain extender.

[0030] Optionally, in some embodiments of this application, R3 and R4 are each independently selected from...

[0031]

[0032] One or more of the following, where * represents a connection site; and / or

[0033] The molar ratio of the first reactant to the second reactant is 1:0.49–0.51; and / or

[0034] The molar ratio of the third reactant to the fourth reactant is 1:0.49–0.51; and / or

[0035] The reaction of the first reactant with the second reactant to obtain the first chain extender is carried out at -15 to -5°C; and / or

[0036] The reaction of the third reactant with the fourth reactant to obtain the second chain extender is carried out at -15 to -5°C; and / or

[0037] The method for preparing the first chain extender further includes: providing an acid-binding agent, and mixing the acid-binding agent with the first reactant and the second reactant before reacting to obtain the first chain extender; and / or

[0038] The preparation method of the second chain extender further includes: providing an acid-binding agent, and mixing the acid-binding agent with the third reactant and the fourth reactant before reacting to obtain the second chain extender.

[0039] Optionally, in some embodiments of this application, the polyurethane prepolymer, the first chain extender, and the second chain extender are mixed, and the reaction to obtain polyurethane is carried out in a protective gas environment at 50-100°C; and / or the method for preparing polyurethane further includes: providing a catalyst, and mixing the catalyst with the polyurethane prepolymer, the first chain extender, and the second chain extender before the reaction to obtain polyurethane.

[0040] The polyurethane elastomer provided in this application has at least two hydrogen bond donor sites and hydrogen bond acceptor sites in both the first and second molecular segments of its molecular backbone. Therefore, the polyurethane elastomer provided in this application possesses a supramolecular cross-linked network formed by multiple, multi-level hydrogen bonds and other non-covalent interactions. The multiple hydrogen bonds formed by the two or more hydrogen bond donor sites and hydrogen bond acceptor sites ensure excellent thermomechanical stability of the elastomer at high temperatures. Furthermore, the arrangement of the first and second molecular segments enables the formation of multi-level hydrogen bonds within the polyurethane elastomer. Under external load, the stepwise dissociation of these multi-level non-covalent interactions (hydrogen bonds) gives the elastomer excellent toughness. In addition, under specific conditions (e.g., temperatures greater than 150°C or 100°C, with DMF as the solvent), the non-covalent network of the polyurethane elastomer provided in this invention can undergo dynamic dissociation and recombination, which endows the polyurethane elastomer with closed-loop recycling capability under specific conditions. In summary, the elastomer provided by this invention has excellent thermal stability, solvent resistance, high strength, high toughness, and closed-loop recyclability, making it highly promising for application in high-end fields such as aerospace and functional electronic devices. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart of the polyurethane elastomer preparation method provided in this application. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0044] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0045] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0046] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0047] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0048] The structural formulas and molecular weights of some of the chemical reagents used in this application are described below:

[0049] Polytetramethylene ether glycol-2000 (PTMEG-2000): n is an integer from 20 to 30, and the number-average molecular weight is 2000;

[0050] Dicyclohexylmethane diisocyanate (HMDI): Molecular weight = 262.35;

[0051] Oxaloyl chloride: Molecular weight = 126.93;

[0052] 4-Hydroxybenzoylhydrazine: Molecular weight = 152.15;

[0053] 4-Hydroxybutyric acid hydrazide: Molecular weight = 118.14;

[0054] p-Aminophenol: Molecular weight = 109.13;

[0055] 4-Amino-1-butanol: Molecular weight = 89.14;

[0056] Triethylamine: Molecular weight = 101.19.

[0057] This application provides a polyurethane elastomer, wherein at least a portion of the polyurethane molecular backbone includes a first molecular chain segment and a second molecular chain segment. The molecular structures of the first molecular chain segment and the second molecular chain segment each independently include at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites. The chemical structures of the first molecular chain segment and the second molecular chain segment are different.

[0058] Since both the first and second molecular segments contain at least two hydrogen bond donor sites and hydrogen bond acceptor sites, multiple hydrogen bonds can be formed in the polyurethane elastomer. Furthermore, because the first and second molecular segments have different chemical structures, they can each generate hydrogen bonding independently. Therefore, the polyurethane elastomer provided in this application can also form multi-level hydrogen bonds. In this way, the multiple strong hydrogen bond crosslinking points ensure that the elastomer maintains excellent stability at high temperatures and in various organic solvents, while the multi-level strong hydrogen bond crosslinking points can act as "sacrificial bonds" to toughen the elastomer.

[0059] It should be noted that, in this application, "hydrogen bond donor site" refers to a hydrogen atom bonded to a highly electronegative atom, while "hydrogen bond acceptor site" refers to an atom B containing a lone pair of electrons and carrying a partial negative charge, such as an F atom, an O atom, or an N atom. For example, when the chemical structure of the first molecular chain segment is... In this case, the first molecular chain segment contains 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites. How to determine whether a hydrogen atom can become a hydrogen bond donor site and whether an atom can become a hydrogen bond acceptor site is basic common sense for those skilled in the art, and will not be elaborated upon here.

[0060] In some embodiments, the hydrogen bond donor sites and hydrogen bond acceptor sites in the first molecular chain segment are the same.

[0061] In some embodiments, the hydrogen bond donor sites and hydrogen bond acceptor sites in the second molecular chain segment are the same.

[0062] Preferably, in some embodiments, the hydrogen bond donor sites and hydrogen bond acceptor sites in the first molecular chain segment and the second molecular chain segment are the same. When the hydrogen bond donor sites and hydrogen bond acceptor sites are the same, it is easier to form a continuous hydrogen bond network. Furthermore, when the hydrogen bond donor sites and hydrogen bond acceptor sites are the same, the formed hydrogen bond network is more regular, which is beneficial to improving the mechanical properties of polyurethane elastomers.

[0063] In some embodiments, at least a portion of the polyurethane's molecular backbone structure is as follows:

[0064]

[0065] Where R1 represents the first molecular chain segment, R2 represents the second molecular chain segment, x and y represent the molar amounts of the first and second molecular chain segments, respectively, and the value of x ranges from 0.4 to 0.6, and y = 1 - x;

[0066] The chemical structure of R is: Where n is an integer between 20 and 30. * represents a connection site.

[0067] In some embodiments, either R1 or R2 includes a rigid group while the other includes only a flexible group. The rigid group is selected from one or more of an aromatic ring with 6 to 10 substituted or unsubstituted carbon atoms, or an aliphatic ring with 6 to 10 substituted or unsubstituted carbon atoms. The flexible group is a hydrocarbon group with 2 to 5 substituted or unsubstituted carbon atoms. By simultaneously introducing rigid and flexible supramolecular segments into the molecular chain of the polyurethane elastomer, they can work synergistically to further toughen the polyurethane elastomer.

[0068] In some embodiments, R1 and R2 are each independently selected from:

[0069]

[0070] One or more of the above groups, where * indicates a linking site. In this application, R1 and R2 are specifically selected from the above groups. Thus, compared to the prior art, the polyurethane chemical structure provided by this application can enhance the density of hydrogen bonds formed in the material and improve the mechanical properties of the polyurethane.

[0071] It is understood that although R1 and R2 are each independently selected from the aforementioned groups, in order to form multi-level hydrogen bonding in the polyurethane elastomer, the chemical structures of R1 and R2 in the polyurethane elastomer provided by this invention should be different. In other words, the independent determination of R1 and R2 requires the premise that R1 and R2 have different chemical structures.

[0072] In some embodiments, the first molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites, and the second molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites. In some embodiments, the first molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites, and the second molecular chain segment includes four hydrogen bond donor sites and four hydrogen bond acceptor sites. In some embodiments, the first molecular chain segment includes four hydrogen bond donor sites and four hydrogen bond acceptor sites, and the second molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites. In some embodiments, the first molecular chain segment includes four hydrogen bond donor sites and four hydrogen bond acceptor sites, and the second molecular chain segment includes four hydrogen bond donor sites and four hydrogen bond acceptor sites.

[0073] Preferably, when the first molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, the first molecular chain segment and the second molecular chain segment can each form a quadruple hydrogen bond, thus resulting in a polyurethane elastomer with superior mechanical properties.

[0074] Accordingly, this application provides a method for preparing a polyurethane elastomer; please refer to [link to method]. Figure 1 ,include:

[0075] S01: Provides polyurethane prepolymer, a first chain extender, and a second chain extender;

[0076] The polyurethane prepolymer has isocyanate groups at both ends of its molecule, and both the first chain extender and the second chain extender have a hydroxyl group at both ends of their molecular structures. Thus, the molecular chain can be extended through the reaction of the hydroxyl group and the isocyanate group, resulting in a polyurethane elastomer.

[0077] S02: Mix polyurethane prepolymer, first chain extender and second chain extender, and react to obtain polyurethane;

[0078] The molecular structures of the first chain extender and the second chain extender each independently include at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites.

[0079] Understandably, after reacting the polyurethane prepolymer, the first chain extender, and the second chain extender, the first chain extender will form the first molecular segment of the polyurethane elastomer molecular chain, and the second chain extender will form the second molecular segment of the polyurethane elastomer molecular chain. To make the mixing reaction more efficient, the mixing reaction can be carried out in a solvent. After the reaction is complete, the solvent is removed to obtain the polyurethane elastomer.

[0080] In some embodiments, the method for preparing the first chain extender includes:

[0081] Provides a first reactant and a second reactant. The chemical structure of the first reactant is NH₂-R₃-OH, wherein R₃ is selected from one or more of an aromatic group with 6 to 10 substituted or unsubstituted carbon atoms and a hydrocarbon group with 2 to 5 substituted or unsubstituted carbon atoms; the chemical structure of the second reactant is... Where X is a halogen element; and

[0082] The first reactant and the second reactant are mixed to produce the first chain extender.

[0083] The preparation methods of the second chain extender include:

[0084] Provide a third reactant and a fourth reactant. The chemical structure of the third reactant is NH₂-R₄-OH, wherein R₄ is selected from one or more of an aromatic group with 6 to 10 substituted or unsubstituted carbon atoms and a hydrocarbon group with 2 to 5 substituted or unsubstituted carbon atoms; the chemical structure of the fourth reactant is... Where X is a halogen element; and

[0085] The third reactant and the fourth reactant are mixed to produce the second chain extender.

[0086] Preferably, X can be the Cl element.

[0087] In some embodiments, R3 and R4 are each independently selected from... One or more of the following, where * represents a connection site.

[0088] In some embodiments, the molar ratio of the first reactant to the second reactant can be 1:0.49 to 0.51.

[0089] In some embodiments, the molar ratio of the third reactant to the fourth reactant can be 1:0.49 to 0.51.

[0090] In some embodiments, the reaction of the first reactant with the second reactant to obtain the first chain extender can be carried out at -15 to -5°C.

[0091] In some embodiments, the reaction of the third reactant with the fourth reactant to obtain the second chain extender can be carried out at -15 to -5°C.

[0092] In some embodiments, the method for preparing the first chain extender further includes: providing an acid-binding agent, and mixing the acid-binding agent with the first reactant and the second reactant before reacting to obtain the first chain extender.

[0093] In some embodiments, the method for preparing the second chain extender further includes: providing an acid-binding agent, and mixing the acid-binding agent with a third reactant and a fourth reactant before reacting to obtain the second chain extender.

[0094] Specifically, the acid-binding agent can be triethylamine.

[0095] In some embodiments, the polyurethane prepolymer, the first chain extender, and the second chain extender are mixed, and the reaction to obtain polyurethane is carried out in a protective gas environment at 50–100°C.

[0096] In some embodiments, the method for preparing polyurethane further includes: providing a catalyst, wherein the catalyst is mixed with a polyurethane prepolymer, a first chain extender, and a second chain extender before the reaction yields polyurethane. Specifically, the catalyst may be dibutyltin dilaurate.

[0097] Example 1

[0098] This embodiment provides a polyurethane elastomer and its preparation method, specifically including:

[0099] Step 1: Weigh 10g of polytetramethylene ether glycol-2000 (PTMEG-2000, 0.005mol) and 100g of anhydrous DMF into a 250ml three-necked flask. Stir at 60℃ until PTMEG is completely dissolved. Add 2.63g of dicyclohexylmethane diisocyanate (HMDI, 0.01mol) and 0.1ml of dibutyltin dilaurate (catalyst). Under nitrogen protection, react at 60℃ for 3h to obtain a prepolymer with isocyanate end groups. Its specific structural formula is shown below:

[0100] Where n is an integer between 20 and 30;

[0101] Step 2: Add 1.52 g of 4-hydroxybenzoyl hydrazide (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, heat to 80 °C, and stir until the 4-hydroxybenzoyl hydrazide is completely dissolved. Transfer the three-necked flask to a -10 °C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80 °C. Wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0102]

[0103] Step 3: Add 1.09 g of p-aminophenol (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, and stir until the p-aminophenol is completely dissolved. Transfer the three-necked flask to a -10°C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine in the system by rotary evaporation at 80°C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0104]

[0105] Step 4: Dissolve 0.89 g (0.0025 mol) of the product obtained in Step 2 and 0.68 g (0.0025 mol) of the product obtained in Step 3 in 10 ml of anhydrous DMF; then add the DMF solution dropwise to the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is complete, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, the specific structural formula of which is shown below:

[0106]

[0107] Where R is Where n is an integer between 20 and 30.

[0108] Example 2

[0109] This embodiment provides a polyurethane elastomer and its preparation method, specifically including:

[0110] Step 1: Weigh 10g of polytetramethylene ether glycol-2000 (PTMEG-2000, 0.005mol) and 100g of anhydrous DMF into a 250ml three-necked flask. Stir at 60℃ until PTMEG is completely dissolved. Add 2.63g of dicyclohexylmethane diisocyanate (HMDI, 0.01mol) and 0.1ml of dibutyltin dilaurate (catalyst). Under nitrogen protection, react at 60℃ for 3h to obtain a prepolymer with isocyanate end groups. Its specific structural formula is shown below:

[0111] Where n is an integer between 20 and 30;

[0112] Step 2: Add 1.52 g of 4-hydroxybenzoyl hydrazide (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, heat to 80 °C, and stir until the 4-hydroxybenzoyl hydrazide is completely dissolved. Transfer the three-necked flask to a -10 °C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80 °C. Wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0113]

[0114] Step 3: Add 0.89 g of 4-amino-1-butanol (0.01 mol) and 50 ml of tetrahydrofuran to a 150 ml three-necked flask, and stir until the 4-amino-1-butanol is completely dissolved. Transfer the three-necked flask to a -10°C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80°C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0115]

[0116] Step 4: Dissolve 0.89 g (0.0025 mol) of the product obtained in Step 2 and 0.58 g (0.0025 mol) of the product obtained in Step 3 in 10 ml of anhydrous DMF; then add the DMF solution dropwise to the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is complete, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, the specific structural formula of which is shown below:

[0117]

[0118] Where R is Where n is an integer between 20 and 30.

[0119] Example 3

[0120] This embodiment provides a polyurethane elastomer and its preparation method, specifically including:

[0121] Step 1: Weigh 10g of polytetramethylene ether glycol-2000 (PTMEG-2000, 0.005mol) and 100g of anhydrous DMF into a 250ml three-necked flask. Stir at 60℃ until PTMEG is completely dissolved. Add 2.63g of dicyclohexylmethane diisocyanate (HMDI, 0.01mol) and 0.1ml of dibutyltin dilaurate (catalyst). Under nitrogen protection, react at 60℃ for 3h to obtain a prepolymer with isocyanate end groups. Its specific structural formula is shown below:

[0122] Where n is an integer between 20 and 30;

[0123] Step 2: Add 1.18 g of 4-hydroxybutyrate hydrazine (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, heat to 80 °C, and stir until the 4-hydroxybenzoyl hydrazine is completely dissolved. Transfer the three-necked flask to a -10 °C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80 °C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0124]

[0125] Step 3: Add 1.09 g of p-aminophenol (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, and stir until the p-aminophenol is completely dissolved. Transfer the three-necked flask to a -10°C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine in the system by rotary evaporation at 80°C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0126]

[0127] Step 4: Dissolve 0.72 g (0.0025 mol) of the product obtained in Step 2 and 0.68 g (0.0025 mol) of the product obtained in Step 3 in 10 ml of anhydrous DMF; then add the DMF solution dropwise to the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is complete, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, the specific structural formula of which is shown below:

[0128]

[0129] Where R is Where n is an integer between 20 and 30.

[0130] Example 4

[0131] This embodiment provides a polyurethane elastomer and its preparation method, specifically including:

[0132] Step 1: Weigh 10g of polytetramethylene ether glycol-2000 (PTMEG-2000, 0.005mol) and 100g of anhydrous DMF into a 250ml three-necked flask. Stir at 60℃ until PTMEG is completely dissolved. Add 2.63g of dicyclohexylmethane diisocyanate (HMDI, 0.01mol) and 0.1ml of dibutyltin dilaurate (catalyst). Under nitrogen protection, react at 60℃ for 3h to obtain a prepolymer with isocyanate end groups. Its specific structural formula is shown below:

[0133] Where n is an integer between 20 and 30;

[0134] Step 2: Add 1.18 g of 4-hydroxybutyrate hydrazine (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, heat to 80 °C, and stir until the 4-hydroxybenzoyl hydrazine is completely dissolved. Transfer the three-necked flask to a -10 °C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80 °C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0135]

[0136] Step 3: Add 0.89 g of 4-amino-1-butanol (0.01 mol) and 50 ml of tetrahydrofuran to a 150 ml three-necked flask, and stir until the 4-amino-1-butanol is completely dissolved. Transfer the three-necked flask to a -10°C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80°C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0137]

[0138] Step 4: Dissolve 0.72 g (0.0025 mol) of the product obtained in Step 2 and 0.58 g (0.0025 mol) of the product obtained in Step 3 in 10 ml of anhydrous DMF; then add the DMF solution dropwise to the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is complete, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, the specific structural formula of which is shown below:

[0139]

[0140] Where R is Where n is an integer between 20 and 30.

[0141] Example 5

[0142] This embodiment provides a polyurethane elastomer and its preparation method, specifically including:

[0143] Step 1: Weigh 10g of polytetramethylene ether glycol-2000 (PTMEG-2000, 0.005mol) and 100g of anhydrous DMF into a 250ml three-necked flask. Stir at 60℃ until PTMEG is completely dissolved. Add 2.63g of dicyclohexylmethane diisocyanate (HMDI, 0.01mol) and 0.1ml of dibutyltin dilaurate (catalyst). Under nitrogen protection, react at 60℃ for 3h to obtain a prepolymer with isocyanate end groups. Its specific structural formula is shown below:

[0144] Where n is an integer between 20 and 30;

[0145] Step 2: Add 1.52 g of 4-hydroxybenzoyl hydrazide (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, heat to 80 °C, and stir until the 4-hydroxybenzoyl hydrazide is completely dissolved. Transfer the three-necked flask to a -10 °C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80 °C. Wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0146]

[0147] Step 3: Add 1.18 g of 4-hydroxybutyrate hydrazine (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, heat to 80 °C, and stir until the 4-hydroxybenzoyl hydrazine is completely dissolved. Transfer the three-necked flask to a -10 °C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80 °C. Wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0148]

[0149] Step 4: Dissolve 0.89 g (0.0025 mol) of the product obtained in Step 2 and 0.72 g (0.0025 mol) of the product obtained in Step 3 in 10 ml of anhydrous DMF; then add the DMF solution dropwise to the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is complete, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, the specific structural formula of which is shown below:

[0150]

[0151] Where R is Where n is an integer between 20 and 30.

[0152] Example 6

[0153] This embodiment provides a polyurethane elastomer and its preparation method, specifically including:

[0154] Step 1: Weigh 10g of polytetramethylene ether glycol-2000 (PTMEG-2000, 0.005mol) and 100g of anhydrous DMF into a 250ml three-necked flask. Stir at 60℃ until PTMEG is completely dissolved. Add 2.63g of dicyclohexylmethane diisocyanate (HMDI, 0.01mol) and 0.1ml of dibutyltin dilaurate (catalyst). Under nitrogen protection, react at 60℃ for 3h to obtain a prepolymer with isocyanate end groups. Its specific structural formula is shown below:

[0155] Where n is an integer between 20 and 30;

[0156] Step 2: Add 1.09 g of p-aminophenol (0.01 mol) and 100 ml of dioxane to a 150 ml three-necked flask, and stir until the p-aminophenol is completely dissolved. Transfer the three-necked flask to a -10°C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine in the system by rotary evaporation at 80°C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0157]

[0158] Step 3: Add 0.89 g of 4-amino-1-butanol (0.01 mol) and 50 ml of tetrahydrofuran to a 150 ml three-necked flask, and stir until the 4-amino-1-butanol is completely dissolved. Transfer the three-necked flask to a -10°C low-temperature ethanol bath, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), and keep stirring. Slowly add 0.63 g of oxaloyl chloride (0.005 mol) dropwise through a 1 ml syringe. After the addition is complete, react for 30 min. Remove the dioxane and residual triethylamine by rotary evaporation at 80°C. Then wash with deionized water to remove the byproduct triethylamine hydrochloride, obtaining a white powder product. Its specific structural formula and reaction equation are shown below:

[0159]

[0160] Step 4: Dissolve 0.68 g (0.0025 mol) of the product obtained in Step 2 and 0.58 g (0.0025 mol) of the product obtained in Step 3 in 10 ml of anhydrous DMF; then add the DMF solution dropwise to the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is complete, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, the specific structural formula of which is shown below:

[0161]

[0162] Where R is Where n is an integer between 20 and 30.

[0163] The comparative example was commercially available polyurethane elastomer TPU WHT-1190, purchased from Wanhua Chemical Group Co., Ltd.

[0164] The mechanical properties and reprocessing properties of the polyurethane elastomers provided in Examples 1 to 6 and the comparative examples were tested, and the test results are shown in Table 1.

[0165] Table 1

[0166]

[0167] The mechanical property tests were performed according to the standard ASTM D412. The repeated hot-working experiment involved cutting the elastomer into small pieces, placing them in a 10cm*10cm*1mm mold frame, and hot-pressing them on a hot press at 200℃, 5MPa, and 10min. After hot pressing, the pieces were cooled and set at room temperature. The solution processing experiment involved cutting the elastomer into small pieces, placing them in a round-bottom flask, adding 20 times the mass of DMF, heating to 120℃, and stirring until the elastomer was completely dissolved. The solution was then poured into a polytetrafluoroethylene dish, placed in a vacuum oven, and vacuum-dried at 100℃ and -0.08MPa for 12h to obtain the polyurethane elastomer.

[0168] The experimental results show that the polyurethane elastomer provided in this application has significantly improved performance in all aspects compared with the prior art. In particular, Example 5 exhibits better overall performance due to the formation of quadruple hydrogen bonds and the fact that the first and second molecular segments are rigid and flexible segments, respectively.

[0169] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A polyurethane elastomer, characterized in that, The molecular backbone of at least part of the polyurethane includes a first molecular chain segment and a second molecular chain segment, each of which independently includes at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites in its molecular structure, and the first molecular chain segment and the second molecular chain segment have different chemical structures. The hydrogen bond donor sites and hydrogen bond acceptor sites are the same in the first molecular chain segment; The hydrogen bond donor sites and hydrogen bond acceptor sites are the same in the second molecular chain segment; At least part of the molecular backbone structure of the polyurethane is as follows: Where R1 represents the first molecular chain segment, R2 represents the second molecular chain segment, x and y represent the molar amounts of the first and second molecular chain segments, respectively, and the value of x ranges from 0.4 to 0.6, and y = 1 - x; The chemical structure of R is: , where n is an integer from 20 to 30; * indicates a connection site; R1 and R2 are each independently selected from: , , , ; One or more of the following, where * represents a connection site.

2. The polyurethane elastomer according to claim 1, characterized in that, The first molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites, and the second molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites. or The first molecular chain segment includes two hydrogen bond donor sites and two hydrogen bond acceptor sites, and the second molecular chain segment includes four hydrogen bond donor sites and four hydrogen bond acceptor sites. or The first molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular chain segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites; or The first molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites.

3. The method for preparing the polyurethane elastomer according to any one of claims 1 to 2, characterized in that, include: Provide polyurethane prepolymer, a first chain extender, and a second chain extender; and The polyurethane prepolymer, the first chain extender, and the second chain extender are mixed and reacted to obtain polyurethane. The molecular structures of the first chain extender and the second chain extender each independently include at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites.

4. The preparation method according to claim 3, characterized in that, The preparation method of the first chain extender includes: Provides a first reactant and a second reactant, wherein the first reactant has the chemical structure NH₂-R₃-OH, and the second reactant has the chemical structure... Where X is a halogen element; and The first reactant and the second reactant are mixed to react and obtain the first chain extender; The preparation method of the second chain extender includes: A third reactant and a fourth reactant are provided, wherein the chemical structure of the third reactant is NH₂-R₄-OH, and the chemical structure of the fourth reactant is... Where X is a halogen element; and The third reactant and the fourth reactant are mixed to obtain the second chain extender; R3 and R4 are each independently selected from... , , , One or more of the following, where * represents a connection site.

5. The preparation method according to claim 4, characterized in that, The molar ratio of the first reactant to the second reactant is 1:0.49~0.51; and / or The molar ratio of the third reactant to the fourth reactant is 1:0.49~0.51; and / or The reaction of the first reactant with the second reactant to obtain the first chain extender is carried out at -15 to -5°C; and / or The reaction of the third reactant with the fourth reactant to obtain the second chain extender is carried out at -15 to -5°C. and / or The method for preparing the first chain extender further includes: providing an acid-binding agent, and mixing the acid-binding agent with the first reactant and the second reactant before reacting to obtain the first chain extender; and / or The preparation method of the second chain extender further includes: providing an acid-binding agent, and mixing the acid-binding agent with the third reactant and the fourth reactant before reacting to obtain the second chain extender.

6. The preparation method according to claim 3, characterized in that, The polyurethane prepolymer, the first chain extender, and the second chain extender are mixed, and the reaction to obtain polyurethane is carried out in a protective gas environment at 50~100°C; and / or The method for preparing the polyurethane further includes: providing a catalyst, and mixing the catalyst with the polyurethane prepolymer, the first chain extender and the second chain extender before reacting to obtain the polyurethane.

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