Polyurethane elastomer and preparation method thereof

Abstract

The invention discloses a polyurethane elastomer and a preparation method thereof, and relates to the field of high polymer materials. At least part of a molecular main chain in the polyurethane elastomer comprises 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 respectively and 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 invention has excellent toughness and stability.

Description

Technical Field

[0001] This application relates to the technical field of polymer materials, and particularly relates to polyurethane elastomers and their preparation methods. Background Art

[0002] Thermoplastic polyurethane elastomers combine the high elasticity of rubber and the excellent abrasion resistance, wear resistance, and repeat processing ability of polyurethane plastics, and are widely used in fields such as shoe materials, the automotive industry, electronic products, and sports goods.

[0003] Polyurethane elastomers usually consist of polyether or polyester soft segments and polyurethane hard segments, and a microphase separation structure of a soft phase - hard phase is formed due to the thermodynamic difference between the hard and soft segments. The hard regions act as physical cross - link points to enhance and promote resilience. However, compared with traditional vulcanized rubber, thermoplastic polyurethane elastomers lack a stable covalent cross - link network, resulting in inferior stability, mechanical strength, toughness, and fatigue resistance. Therefore, the "sacrificial bond" strategy based on supramolecular chemistry is often used for the reinforcement and toughening of polyurethane elastomers, such as introducing non - covalent interactions such as hydrogen bonds, dipole - dipole interactions, and coordination bonds into polyurethane elastomers; these weak interactions are first broken and absorb energy when encountering deformation.

[0004] However, due to the dynamic and reversible nature of non - covalent interactions, the non - covalent cross - link network of polyurethane elastomers is easily damaged under 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 with excellent toughness and stability.

[0006] In the embodiments of this application, a polyurethane elastomer is provided. At least part of the molecular main chain of the polyurethane 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 2 hydrogen - bond donor sites and at least 2 hydrogen - bond acceptor sites, and 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 number of hydrogen - bond donor sites in the first molecular chain segment is the same as the number of hydrogen - bond acceptor sites; and / or

[0008] the number of hydrogen - bond donor sites in the second molecular chain segment is the same as the number of hydrogen - bond acceptor sites.

[0009] Optionally, in some embodiments of this application, the molecular main chain structure of at least part of the polyurethane is:

[0010]

[0011] , wherein, R1 represents a first molecular chain segment, R2 represents a second molecular chain segment, x and y respectively represent the molar amounts of the first molecular chain segment and the second molecular chain segment, the value range of x is 0.4 to 0.6, and y = 1 - x;

[0012] The chemical structure of R is: wherein n is an integer from 20 to 30.

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

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

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

[0016] Optionally, in some embodiments of the present application, the first molecular chain segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites, and the second molecular chain segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites; or

[0017] the first molecular chain segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites, and the second molecular chain segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites; or

[0018] 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

[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] Correspondingly, the present application provides a method for preparing a polyurethane elastomer, including:

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

[0022] mixing the polyurethane prepolymer, the first chain extender, and the second chain extender, and reacting to obtain a polyurethane;

[0023] wherein, the molecular structures of the first chain extender and the second chain extender each independently include at least 2 hydrogen bond donor sites and at least 2 hydrogen bond acceptor sites.

[0024] Optionally, in some embodiments of the present application, the preparation method of the first chain extender includes:

[0025] Providing 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 a substituted or unsubstituted aryl group having 6 to 10 carbon atoms and a substituted or unsubstituted hydrocarbon group having 2 to 5 carbon atoms; the chemical structure of the second reactant is wherein X is a halogen element; and

[0026] Mixing the first reactant and the second reactant, and reacting to obtain the first chain extender;

[0027] The preparation method of the second chain extender includes:

[0028] Providing 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 a substituted or unsubstituted aryl group having 6 to 10 carbon atoms and a substituted or unsubstituted hydrocarbon group having 2 to 5 carbon atoms; the chemical structure of the fourth reactant is wherein X is a halogen element; and

[0029] Mixing the third reactant and the fourth reactant, and reacting to obtain the second chain extender.

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

[0031]

[0032] one or more of them, wherein * represents the connection site; and / or

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

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

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

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

[0037] The preparation method of 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 the present application, mixing the polyurethane prepolymer, the first chain extender, and the second chain extender, and reacting to obtain the polyurethane is carried out in a protective gas environment at 50-100 °C; and / or the preparation method of 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.

[0040] Both the first molecular chain segment and the second molecular chain segment in the molecular main chain of the polyurethane elastomer provided by the present application have at least two or more hydrogen bond donor sites and hydrogen bond acceptor sites. Therefore, the polyurethane elastomer provided by the present application has a supramolecular cross-linked network formed by multiple and multi-level non-covalent interactions such as multiple and multi-level hydrogen bonds. The multiple hydrogen bonds formed by two or more hydrogen bond donor sites and hydrogen bond acceptor sites ensure that the elastomer maintains excellent thermo-mechanical stability at high temperatures; and the arrangement of the first molecular chain segment and the second molecular chain segment can form multi-level hydrogen bonds inside the polyurethane elastomer. When an external load is applied, the gradual dissociation of the multi-level non-covalent interactions (hydrogen bonds) makes the elastomer have excellent toughness. In addition, under specific conditions (for example, the temperature is greater than 150 °C or 100 °C, and DMF is used as the solvent), the non-covalent network of the polyurethane elastomer provided by the present invention can undergo dynamic dissociation and recombination, which endows the polyurethane elastomer with the ability of closed-loop recycling under specific conditions. In summary, the elastomer provided by the present invention has excellent thermal stability, solvent resistance, high strength, high toughness, and closed-loop recycling performance, and has great application prospects in high-end fields such as aerospace and functional electronic devices. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a flow chart of the preparation method of the polyurethane elastomer provided by the present application. Detailed Embodiments

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation manners described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0044] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" usually refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels, and no numerical requirements are imposed or an order is established.

[0045] In the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B may be singular or plural.

[0046] In the present application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "at least one (item)" or similar expressions below refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b, or c", or, "at least one (item) of a, b, and c" can all represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0047] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub - ranges and single 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, and this applies regardless of the range. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

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

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

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

[0051] Oxalyl chloride: Molecular weight = 126.93;

[0052] 4 - Hydroxybenzohydrazide: 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] An embodiment of the present application provides a polyurethane elastomer. At least a part of the molecular main chain of the polyurethane 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 2 hydrogen - bond donor sites and at least 2 hydrogen - bond acceptor sites, and the chemical structures of the first molecular chain segment and the second molecular chain segment are different.

[0058] Since both the first molecular chain segment and the second molecular chain segment include at least 2 hydrogen - bond donor sites and hydrogen - bond acceptor sites, multiple hydrogen bonds can be formed in the polyurethane elastomer; and because the chemical structures of the first molecular chain segment and the second molecular chain segment are different, they can independently produce hydrogen - bond interactions. Therefore, multi - level hydrogen bonds can also be formed in the polyurethane elastomer provided by the present application. In this way, multiple strong hydrogen - bond cross - link points ensure the excellent stability of the elastomer at high temperatures and in various organic solvents, and the multi - level strong hydrogen - bond cross - link points can act as "sacrificial bonds" to toughen the elastomer.

[0059] It should be noted that the "hydrogen - bond donor site" in the present application refers to a hydrogen atom connected to an atom with strong electronegativity, and the "hydrogen - bond acceptor site" refers to an atom B with a lone pair of electrons and a partial negative charge, such as F atom, O atom, N atom, etc. For example, when the chemical structure of the first molecular chain segment is When there are, 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 be a hydrogen bond donor site and whether an atom can be a hydrogen bond acceptor site is basic common sense mastered by those skilled in the art and will not be elaborated 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 both 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. Further, when the hydrogen bond donor sites and hydrogen bond acceptor sites are the same, the formed hydrogen bond network is more regular. Thus, it is beneficial to improve the mechanical properties of the polyurethane elastomer.

[0063] In some embodiments, at least part of the molecular main chain structure of the polyurethane is:

[0064]

[0065] , where R1 represents the first molecular chain segment, R2 represents the second molecular chain segment, x and y respectively represent the molar amounts of the first molecular chain segment and the second molecular chain segment, the value range of x is 0.4 - 0.6, and y = 1 - x;

[0066] The chemical structure of R is: where n is an integer from 20 to 30. Where * represents the connection site

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

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

[0069]

[0070] One or more of them, where * represents the connection site. R1 and R2 in the present application are particularly selected from the above groups. Thus, compared with the prior art, the polyurethane chemical structure provided by the present application can enhance the density of hydrogen bonds formed in the material and improve the mechanical properties of the polyurethane.

[0071] It can be understood that although R1 and R2 are each independently selected from the aforementioned groups, in order to form a multi-level hydrogen bond interaction in the polyurethane elastomer, the chemical structures of R1 and R2 in the polyurethane elastomer provided by the present invention should be different. In other words, the independent determination of R1 and R2 should be based on the premise that the chemical structures of R1 and R2 are different.

[0072] In some embodiments, the first molecular segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites, and the second molecular segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites. In some embodiments, the first molecular segment includes 2 hydrogen bond donor sites and 2 hydrogen bond acceptor sites, and the second molecular segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites. In some embodiments, 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. In some embodiments, the first molecular segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites.

[0073] Preferably, when the first molecular segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, and the second molecular segment includes 4 hydrogen bond donor sites and 4 hydrogen bond acceptor sites, the first molecular segment and the second molecular segment can each form quadruple hydrogen bonds. Thus, the mechanical properties of the obtained polyurethane elastomer are more excellent.

[0074] Correspondingly, the present application provides a method for preparing a polyurethane elastomer. Please refer to Figure 1 , including:

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

[0076] The two ends of the polyurethane prepolymer molecule have isocyanate groups, and both ends of the molecular structures of the first chain extender and the second chain extender contain a hydroxyl group. Thus, through the reaction of the hydroxyl group and the isocyanate group, the growth of the molecular chain can be achieved to obtain a polyurethane elastomer.

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

[0078] Wherein, the molecular structures of the first chain extender and the second chain extender each independently include at least 2 hydrogen bond donor sites and at least 2 hydrogen bond acceptor sites.

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

[0080] In some embodiments, the preparation method of the first chain extender includes:

[0081] Providing 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 a substituted or unsubstituted aryl group with 6 to 10 carbon atoms, a substituted or unsubstituted hydrocarbon group with 2 to 5 carbon atoms; the chemical structure of the second reactant is wherein X is a halogen element; and

[0082] Mixing the first reactant and the second reactant, and reacting to obtain the first chain extender.

[0083] The preparation method of the second chain extender includes:

[0084] Providing 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 a substituted or unsubstituted aryl group with 6 to 10 carbon atoms, a substituted or unsubstituted hydrocarbon group with 2 to 5 carbon atoms; the chemical structure of the fourth reactant is wherein X is a halogen element; and

[0085] Mixing the third reactant and the fourth reactant, and reacting to obtain the second chain extender.

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

[0087] In some embodiments, R3 and R4 are each independently selected from one or more of them, wherein * represents the 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 and the second reactant to obtain the first chain extender can be carried out under the condition of -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 under the condition of -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 the third reactant and the fourth reactant before reacting to obtain the second chain extender.

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

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

[0096] In some embodiments, 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. Specifically, the catalyst can be dibutyltin dilaurate.

[0097] Example 1

[0098] This example provides a polyurethane elastomer and a preparation method thereof, specifically including:

[0099] Step 1: Weigh 10 g of polytetramethylene ether glycol - 2000 (PTMEG - 2000, 0.005 mol) and 100 g of anhydrous DMF and add them to a 250 ml three-necked flask. Stir at 60 °C until the PTMEG is completely dissolved, and then dropwise add 2.63 g of dicyclohexylmethane diisocyanate (HMDI, 0.01 mol) and 0.1 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 3 h to obtain a prepolymer with isocyanate groups at both ends, and its specific structural formula is as follows:

[0100] Where n is an integer from 20 to 30;

[0101] Step 2: Take 1.52 g of 4-hydroxybenzohydrazide (0.01 mol) and 100 ml of dioxane and add them to a 150 ml three-necked flask. Heat to 80 °C and start stirring until the 4-hydroxybenzohydrazide is completely dissolved. Transfer the three-necked flask to a low-temperature ethanol bath at -10 °C, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), keep stirring, and slowly drip 0.63 g of oxalyl chloride (0.005 mol) through a 1 ml syringe. After the dripping is complete, react for 30 min. Rotate and evaporate to remove the dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by-product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0102]

[0103] Step 3: Take 1.09 g of p-aminophenol (0.01 mol) and 100 ml of dioxane and add them to a 150 ml three-necked flask. Start stirring until the p-aminophenol is completely dissolved. Transfer the three-necked flask to a low-temperature ethanol bath at -10 °C, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), keep stirring, and slowly drip 0.63 g of oxalyl chloride (0.005 mol) through a 1 ml syringe. After the dripping is complete, react for 30 min. Rotate and evaporate to remove the dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by-product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0104]

[0105] Step 4: Take 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 and dissolve them in 10 ml of anhydrous DMF; then drip the DMF solution into the prepolymer solution obtained in Step 1, and drip 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is completed, pour the reaction solution into a polytetrafluoroethylene tray and place it in a vacuum oven. Vacuum dry at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, and its specific structural formula is as follows:

[0106]

[0107] where R is where n is an integer from 20 to 30.

[0108] Example 2

[0109] This example provides a polyurethane elastomer and its preparation method, which specifically includes:

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

[0111] where n is an integer from 20 to 30;

[0112] Step 2: Take 1.52 g of 4 - hydroxybenzohydrazide (0.01 mol) and 100 ml of dioxane and add them to a 150 - ml three - necked flask. Heat to 80 °C, start stirring until 4 - hydroxybenzohydrazide is completely dissolved. Transfer the three - necked flask to a low - temperature ethanol bath at - 10 °C, add 1.2 g of triethylamine (0.012 mol, acid - binding agent), keep stirring, and slowly add 0.63 g of oxalyl chloride (0.005 mol) dropwise through a 1 - ml syringe. After the addition, react for 30 min, rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by - product triethylamine hydrochloride to obtain a white powder product. Its specific structural formula and reaction equation are as follows:

[0113]

[0114] Step 3: Take 0.89 g of 4 - amino - 1 - butanol (0.01 mol) and 50 ml of tetrahydrofuran and add them to a 150 - ml three - necked flask. Start stirring until 4 - amino - 1 - butanol is completely dissolved. Transfer the three - necked flask to a low - temperature ethanol bath at - 10 °C, add 1.2 g of triethylamine (0.012 mol, acid - binding agent), keep stirring, and slowly add 0.63 g of oxalyl chloride (0.005 mol) dropwise through a 1 - ml syringe. After the addition, react for 30 min, rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by - product triethylamine hydrochloride to obtain a white powder product. Its specific structural formula and reaction equation are as follows:

[0115]

[0116] Step 4: Take 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 and dissolve them in 10 ml of anhydrous DMF; then drop the DMF solution into 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 completed, pour the reaction solution into a polytetrafluoroethylene dish, place it in a vacuum oven, and dry it under vacuum at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, and its specific structural formula is as follows:

[0117]

[0118] where R is where n is an integer from 20 to 30.

[0119] Example 3

[0120] This example provides a polyurethane elastomer and its preparation method, which specifically includes:

[0121] Step 1: Weigh 10 g of polytetramethylene ether glycol - 2000 (PTMEG - 2000, 0.005 mol) and 100 g of anhydrous DMF and add them to a 250 ml three - necked flask. Stir at 60 °C until PTMEG is completely dissolved, and then drop 2.63 g of dicyclohexylmethane diisocyanate (HMDI, 0.01 mol) and 0.1 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 3 h to obtain a prepolymer with isocyanate - terminated groups, and its specific structural formula is as follows:

[0122] where n is an integer from 20 to 30;

[0123] Step 2: Take 1.18 g of 4 - hydroxybutyric acid hydrazide (0.01 mol) and 100 ml of dioxane and add them to a 150 ml three - necked flask. Heat to 80 °C, start stirring until 4 - hydroxybenzoyl hydrazide is completely dissolved. Transfer the three - necked flask to a low - temperature ethanol bath at - 10 °C, add 1.2 g of triethylamine (0.012 mol, acid - binding agent), keep stirring, and slowly drop 0.63 g of oxalyl chloride (0.005 mol) through a 1 ml syringe. After dropping, react for 30 min, and rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by - product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0124]

[0125] Step 3: Take 1.09 g of p-aminophenol (0.01 mol) and 100 ml of dioxane and add them to a 150-ml three-necked flask. Start stirring until the p-aminophenol is completely dissolved. Transfer the three-necked flask to a low-temperature ethanol bath at -10 °C, add 1.2 g of triethylamine (0.012 mol, an acid-binding agent), keep stirring, and slowly add 0.63 g of oxalyl chloride (0.005 mol) dropwise through a 1-ml syringe. After the addition, react for 30 min, rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by-product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0126]

[0127] Step 4: Take 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 and dissolve them in 10 ml of anhydrous DMF; then drop the DMF solution into 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, pour the reaction solution into a polytetrafluoroethylene dish, put it into a vacuum oven, and vacuum dry it at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, and its specific structural formula is as follows:

[0128]

[0129] where R is where n is an integer from 20 to 30.

[0130] Example 4

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

[0132] Step 1: Weigh 10 g of polytetramethylene ether glycol - 2000 (PTMEG - 2000, 0.005 mol) and 100 g of anhydrous DMF and add them to a 250-ml three-necked flask. Stir at 60 °C until the PTMEG is completely dissolved, and add 2.63 g of dicyclohexylmethane diisocyanate (HMDI, 0.01 mol) and 0.1 ml of dibutyltin dilaurate (catalyst) dropwise; under nitrogen protection, react at 60 °C for 3 h to obtain a prepolymer with isocyanate groups at the ends, and its specific structural formula is as follows:

[0133] where n is an integer from 20 to 30;

[0134] Step 2: Take 1.18 g of 4-hydroxybutyric hydrazide (0.01 mol) and 100 ml of dioxane and add them to a 150-ml three-necked flask. Heat to 80 °C and start stirring until 4-hydroxybenzoyl hydrazide is completely dissolved. Transfer the three-necked flask to a low-temperature ethanol bath at -10 °C, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), keep stirring, and slowly drip 0.63 g of oxalyl chloride (0.005 mol) through a 1-ml syringe. After the dripping is complete, react for 30 min. Rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by-product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0135]

[0136] Step 3: Take 0.89 g of 4-amino-1-butanol (0.01 mol) and 50 ml of tetrahydrofuran and add them to a 150-ml three-necked flask. Start stirring until 4-amino-1-butanol is completely dissolved. Transfer the three-necked flask to a low-temperature ethanol bath at -10 °C, add 1.2 g of triethylamine (0.012 mol, acid-binding agent), keep stirring, and slowly drip 0.63 g of oxalyl chloride (0.005 mol) through a 1-ml syringe. After the dripping is complete, react for 30 min. Rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by-product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0137]

[0138] Step 4: Take 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 and dissolve them in 10 ml of anhydrous DMF; then drip the DMF solution into the prepolymer solution obtained in Step 1, and drip 0.2 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 12 h. After the reaction is completed, pour the reaction solution into a polytetrafluoroethylene plate, put it into a vacuum oven, and vacuum dry it at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, and its specific structural formula is as follows:

[0139]

[0140] where R is where n is an integer from 20 to 30.

[0141] Example 5

[0142] This example provides a polyurethane elastomer and its preparation method, which specifically includes:

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

[0144] where n is an integer from 20 to 30;

[0145] Step 2: Take 1.52 g of 4 - hydroxybenzohydrazide (0.01 mol) and 100 ml of dioxane and add them to a 150 - ml three - necked flask. Heat to 80 °C and start stirring until the 4 - hydroxybenzohydrazide is completely dissolved. Transfer the three - necked flask to a low - temperature ethanol bath at - 10 °C, add 1.2 g of triethylamine (0.012 mol, acid - binding agent), keep stirring, and slowly add 0.63 g of oxalyl chloride (0.005 mol) dropwise through a 1 - ml syringe. After the addition, react for 30 min. Rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by - product triethylamine hydrochloride to obtain a white powder product. Its specific structural formula and reaction equation are as follows:

[0146]

[0147] Step 3: Take 1.18 g of 4 - hydroxybutyric acid hydrazide (0.01 mol) and 100 ml of dioxane and add them to a 150 - ml three - necked flask. Heat to 80 °C and start stirring until the 4 - hydroxybenzohydrazide is completely dissolved. Transfer the three - necked flask to a low - temperature ethanol bath at - 10 °C, add 1.2 g of triethylamine (0.012 mol, acid - binding agent), keep stirring, and slowly add 0.63 g of oxalyl chloride (0.005 mol) dropwise through a 1 - ml syringe. After the addition, react for 30 min. Rotate and evaporate to remove dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by - product triethylamine hydrochloride to obtain a white powder product. Its specific structural formula and reaction equation are as follows:

[0148]

[0149] Step 4: Take 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 and dissolve them in 10 ml of anhydrous DMF; then drop the DMF solution into 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, pour the reaction solution into a polytetrafluoroethylene dish and place it in a vacuum oven, and dry it under vacuum at 100 °C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, and its specific structural formula is as follows:

[0150]

[0151] where R is where n is an integer from 20 to 30.

[0152] Example 6

[0153] This example provides a polyurethane elastomer and its preparation method, which specifically includes:

[0154] Step 1: Weigh 10 g of polytetramethylene ether glycol - 2000 (PTMEG - 2000, 0.005 mol) and 100 g of anhydrous DMF and add them to a 250 ml three - necked flask. Stir at 60 °C until PTMEG is completely dissolved, then drop 2.63 g of dicyclohexylmethane diisocyanate (HMDI, 0.01 mol) and 0.1 ml of dibutyltin dilaurate (catalyst); under nitrogen protection, react at 60 °C for 3 h to obtain a prepolymer with isocyanate groups at the ends, and its specific structural formula is as follows:

[0155] where n is an integer from 20 to 30;

[0156] Step 2: Take 1.09 g of p - aminophenol (0.01 mol) and 100 ml of dioxane and add them to a 150 ml three - necked flask. Start stirring until p - aminophenol is completely dissolved. Transfer the three - necked flask to a low - temperature ethanol bath at - 10 °C, add 1.2 g of triethylamine (0.012 mol, acid - binding agent), keep stirring, and slowly drop 0.63 g of oxalyl chloride (0.005 mol) through a 1 ml syringe. After dropping, react for 30 min, and rotary evaporate the dioxane and residual triethylamine in the system at 80 °C, and then rinse with deionized water to remove the by - product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0157]

[0158] Step 3: Take 0.89 g of 4-amino-1-butanol (0.01 mol) and 50 ml of tetrahydrofuran and add them to a 150-ml three-necked flask. Start stirring until the 4-amino-1-butanol is completely dissolved. Transfer the three-necked flask to a low-temperature ethanol bath at -10°C, add 1.2 g of triethylamine (0.012 mol, an acid-binding agent), keep stirring, and slowly add 0.63 g of oxalyl chloride (0.005 mol) dropwise through a 1-ml syringe. After the addition, react for 30 min. Rotate and evaporate to remove dioxane and residual triethylamine in the system at 80°C, and then rinse with deionized water to remove the by-product triethylamine hydrochloride to obtain a white powder product; its specific structural formula and reaction equation are as follows:

[0159]

[0160] Step 4: Take 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 and dissolve them in 10 ml of anhydrous DMF; then drop the DMF solution into the prepolymer solution obtained in Step 1, and add 0.2 ml of dibutyltin dilaurate (a catalyst); under nitrogen protection, react at 60°C for 12 h. After the reaction, pour the reaction solution into a polytetrafluoroethylene tray and place it in a vacuum oven. Vacuum dry at 100°C and -0.08 MPa for 12 h to obtain a polyurethane elastomer, and its specific structural formula is as follows:

[0161]

[0162] where R is where n is an integer from 20 to 30.

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

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

[0165] Table 1

[0166]

[0167] Among them, the mechanical property test is carried out in accordance with the standard ASTM D412. The repeated hot processing experiment specifically involves cutting the elastomer into small pieces, placing them in a mold frame of 10 cm * 10 cm * 1 mm, and performing hot pressing on a hot press. The hot pressing temperature is 200 °C, the hot pressing pressure is 5 MPa, and the hot pressing time is 10 min; after hot pressing, it is cooled and shaped at room temperature. The solution processing experiment specifically involves cutting the elastomer into small pieces and then placing them in a round-bottom flask, adding DMF with a mass 20 times that of the elastomer, heating to 120 °C, and keeping stirring until the elastomer is completely dissolved; then pouring the solution into a polytetrafluoroethylene tray, placing it in a vacuum oven, and drying it under vacuum at 100 °C and -0.08 MPa for 12 h to obtain the polyurethane elastomer.

[0168] It can be seen from the experimental results that, compared with the prior art, the polyurethane elastomer provided by this application has significantly improved various properties. Among them, in Example 5, due to the formation of quadruple hydrogen bonds, and the first molecular chain segment and the second molecular chain segment are a rigid chain segment and a flexible chain segment respectively, under the synergistic effect, it exhibits better comprehensive properties.

[0169] The technical solutions provided by the embodiments of this application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those skilled in the art, based on the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A polyurethane elastomer, characterized in that: At least part of the molecular main chain of the polyurethane includes a first molecular segment and a second molecular segment, the molecular structures of the first molecular segment and the second molecular segment each independently include at least 2 hydrogen bond donor sites and at least 2 hydrogen bond acceptor sites, and the chemical structures of the first molecular segment and the second molecular segment are different.

2. The polyurethane elastomer according to claim 1, characterized in that The hydrogen bond donor site and the hydrogen bond acceptor site in the first molecular segment are the same; and / or The hydrogen bond donor site and the hydrogen bond acceptor site in the second molecular segment are the same.

3. The polyurethane elastomer according to claim 2, characterized in that The molecular main chain structure of at least part of the polyurethane is: Wherein, R1 represents the first molecular segment, R2 represents the second molecular segment, x and y represent the molar weight of the first molecular segment and the second molecular segment respectively, the value range of x is 0.4 to 0.6, and y = 1-x; The chemical structure of R is: Wherein n is an integer from 20 to 30; * indicates a connection site.

4. The polyurethane elastomer according to claim 3, characterized in that Either one of R1 and R2 includes a rigid group and the other includes only a flexible group, wherein the rigid group is selected from one or more of a substituted or unsubstituted aromatic ring having 6 to 10 carbon atoms and a substituted or unsubstituted aliphatic ring having 6 to 10 carbon atoms, and the flexible group is a substituted or unsubstituted hydrocarbon group having 2 to 5 carbon atoms.

5. The polyurethane elastomer according to claim 3, characterized in that: The R1 and R2 are each independently selected from: One or more of, where * represents a connection site.

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

7. The method for preparing a polyurethane elastomer according to any one of claims 1 to 6, characterized in that: include: providing a polyurethane prepolymer, a first chain extender, and a second chain extender; and Mixing the polyurethane prepolymer, the first chain extender and the second chain extender to react and obtain polyurethane; Wherein, the molecular structures of the first chain extender and the second chain extender independently include at least two hydrogen bond donor sites and at least two hydrogen bond acceptor sites.

8. The preparation method according to claim 7, characterized in that: The preparation method of the first chain extender comprises: A first reactant and a second reactant are provided, wherein the chemical structure of the first reactant is NH2-R3-OH, wherein R3 is selected from one or more of a substituted or unsubstituted aromatic group having 6 to 10 carbon atoms and a substituted or unsubstituted hydrocarbon group having 2 to 5 carbon atoms; and the chemical structure of the second reactant is wherein X is a halogen element; and Mixing the first reactant and the second reactant to obtain the first chain extender; The preparation method of the second chain extender comprises: A third reactant and a fourth reactant are provided, wherein the chemical structure of the third reactant is NH2-R4-OH, wherein R4 is selected from one or more of a substituted or unsubstituted aromatic group having 6 to 10 carbon atoms and a substituted or unsubstituted hydrocarbon group having 2 to 5 carbon atoms; and the chemical structure of the fourth reactant is wherein X is a halogen element; and The third reactant and the fourth reactant are mixed and reacted to obtain the second chain extender.

9. The preparation method according to claim 8, characterized in that: The R3 and R4 are each independently selected from One or more of which* indicates a site of attachment; and / or 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 first reactant and the second reactant react to obtain the first chain extender at -15 to -5°C; and / or The third reactant reacts with the fourth reactant to obtain the second chain extender at -15 to -5°C; and / or The method for preparing the first chain extender further comprises: 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 method for preparing the second chain extender further includes: providing an acid binder, and mixing the acid binder with the third reactant and the fourth reactant before reacting to obtain the second chain extender.

10. The preparation method according to claim 7, characterized in that: The polyurethane prepolymer, the first chain extender and the second chain extender are mixed to obtain the polyurethane under a protective gas environment at 50 to 100° C.; and / or The preparation method of the polyurethane further comprises: 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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