A degradable polyurethane material and its preparation method and application

Abstract

The present invention provides a degradable polyurethane material, a preparation method thereof, and an application thereof. The present invention belongs to the field of polymer chemistry. The preparation method comprises the following steps: (1) reacting a polyol, a small molecule chain extender, a diisocyanate, and a tridentate ligand to obtain a linear polyurethane; 2) performing a coordination reaction between the linear polyurethane obtained in step (1) and a divalent palladium compound and a monodentate ligand; (3) performing a coordination reaction between an o-phenanthroline ligand and a monovalent copper compound; and (4) mixing the solution obtained in step (3) with a diprimary amine compound and the solution obtained in step (2), removing the solvent, and hot pressing to obtain the degradable polyurethane material. The polyurethane material of the present invention has good tensile strength and toughness and has degradability.

Description

Technical Field

[0001] The invention belongs to the field of polymer chemistry and relates to a degradable polyurethane material and a preparation method and application thereof. Background Art

[0002] With the advancement of science and technology, the demand for high-performance elastomeric materials is increasing. Elastomers with diverse performance characteristics are emerging one after another and are widely used in the automotive industry, healthcare, robotics, and other fields as load-bearing, shock-absorbing, and cushioning materials. People are constantly pursuing elastomeric materials with higher strength and toughness to meet the application needs of various scenarios.

[0003] At the same time, despite the huge global consumption, the repair and recycling of elastomers is difficult to achieve. The large amount of retired elastomer materials will undoubtedly cause serious resource waste and environmental pollution to society. Therefore, it is crucial to give elastomer materials the ability to degrade and recycle.

[0004] Combining a rigid backbone with flexible segments to achieve both rigidity and flexibility is an effective means of achieving higher strength and toughness in materials. For example, in 2024, Yaghi's team (Neumann, et al. "The propensity for covalent organic frameworks to template polymer entanglement" Science 2024, 383, 1337−1343) proposed using dynamically reversible imine bonds to connect metal coordination nodes to construct a covalent organic framework (COF) with a porous crystalline structure. Using this as the rigid backbone, they constructed a network of polymethyl methacrylate and polyimide. The resulting COF junctions possess a unique rigid structure within the network, effectively dispersing the entangled polymer chains throughout the network and perfectly filling the interface with the polymer matrix, significantly improving the toughness and ductility of the composite material. Specifically, this process primarily involves the high-density entanglement formed between the rigid COF structure and the relatively flexible polymer chains. This entanglement requires the polymer chains entangled around it to first release from the backbone under external pressure before further deformation can proceed, thereby achieving effective synergy between the two. Consequently, the energy dissipation mode during composite fracture shifts from primarily dissipating energy through chemical bond breaking to the pulling and extension of the molecular chains from the backbone, thereby macroscopically improving the tensile strength, ductility, and fracture resistance of the polymer-COF composite.

[0005] However, compared with rigid polymethyl methacrylate and polyimide networks, flexible external environments such as polyurethane will provide more space for the movement of molecular chains and are more likely to form high-density entanglements with rigid skeletons, which is expected to achieve better results in enhancing the toughness and strength of the material.

[0006] Wang Tingmei et al. (Xu, et al. Super-Durable, Tough Shape-Memory Polymeric Materials Woven from Interlocking Rigid-Flexible Chains. Adv. Sci.2024, 11, 2406193) and Li Guangfeng et al. (Li, et al., Angew. Chem. Int. Ed. 2022, 61,e202210078; Angew. Chem. 2022, 134, e202210078) in China also attempted to introduce similar strategies into the construction of high-performance elastomeric materials. Although conventional polymerization conditions are difficult to meet the requirements for the construction of crystalline materials such as COF, and the cross-linked skeleton structures they constructed are not all rigid, they still effectively enhance the overall mechanical properties of the material and achieve good tensile strength and toughness.

[0007] Therefore, by introducing a cross-linked skeleton with high rigidity into the polymer network and fully mixing it with the flexible polymer to form high-density molecular chain entanglements between them, it is expected to achieve efficient synergy between the two and obtain better performance in the overall mechanical properties of the material. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the present invention aims to provide a degradable polyurethane material and a preparation method and application thereof.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In one aspect, the present invention provides a method for preparing a degradable polyurethane material, the method comprising the following steps:

[0011] (1) Polyol, small molecule chain extender, diisocyanate and tridentate ligand react to obtain linear polyurethane;

[0012] (2) the linear polyurethane obtained in step (1) undergoes a coordination reaction with a divalent palladium compound and a monodentate ligand to obtain a polyurethane solution containing two metal coordination nodes;

[0013] (3) The o-phenanthroline ligand undergoes a coordination reaction with a monovalent copper compound to obtain a solution containing one of the metal coordination nodes;

[0014] (4) mixing the solution containing one of the metal coordination nodes obtained in step (3) with the optional diprimary amine compound and the polyurethane solution containing the second metal coordination node obtained in step (2), removing the solvent, and hot pressing to obtain the degradable polyurethane material.

[0015] In the present invention, a phenanthroline ligand is coordinated with a monovalent copper compound to form one metal coordination node, a linear polyurethane is obtained by reacting a polyol, a small molecule chain extender, a diisocyanate and a tridentate ligand, and the linear polyurethane is coordinated with a divalent palladium compound and a monodentate ligand to form a second metal coordination node. By mixing the solution obtained in step (3) with the solution obtained in step (2) and hot pressing, the two metal coordination nodes can be connected through a dynamically reversible imine bond, thereby constructing a composite network structure in which flexible segments and a rigid cross-linked skeleton are highly entangled, thereby obtaining a polymer network with excellent mechanical properties and dynamic reversibility. The mechanical properties are derived from the effects of molecular entanglement and metal coordination, while the dynamic reversibility is derived from the imine bonds in the rigid skeleton, so that the network has excellent mechanical properties while also obtaining degradability.

[0016] Preferably, the polyol is selected from polyols terminated with hydroxyl groups at both ends.

[0017] Preferably, the polyol is selected from any one of polytetrahydrofuran, polyethylene glycol or polypropylene glycol, or a combination of at least two thereof.

[0018] Preferably, the number average molecular weight of the polyol is 400-4000 g / mol, for example, 400 g / mol, 600 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2300 g / mol, 2500 g / mol, 2800 g / mol, 3000 g / mol, 3300 g / mol, 3500 g / mol, 3800 g / mol or 4000 g / mol.

[0019] Preferably, the small molecule chain extender is a small molecule diol.

[0020] Preferably, the small molecule diol includes any one of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or 4-phenylenediol, or a combination of at least two thereof.

[0021] Preferably, the diisocyanate is selected from any one or a combination of at least two of hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or dicyclohexylmethane-4,4'-diisocyanate.

[0022] Preferably, the tridentate ligand is the following compound:

[0023] .

[0024] Preferably, the molar ratio of the polyol to the small molecule chain extender in step (1) is (4-10): (0.4-1), for example, 4:0.4, 4:0.5, 4:0.7, 4:0.8, 4:0.9, 4:1, 5:0.4, 5:0.5, 5:0.7, 5:0.8, 5:0.9, 5:1, 6:0.4, 6:0.5, 6:0.7, 6:0.8, 6:0.9, 6: 1, 7:0.4, 7:0.5, 7:0.7, 7:0.8, 7:0.9, 7:1, 8:0.4, 8:0.5, 8:0.7, 8:0.8, 8:0.9, 8:1, 9:0.4, 9:0.5, 9:0.7, 9:0.8, 9:0.9, 9:1, 10:0.4, 10:0.5, 10:0.7, 10:0.8, 10:0.9 or 10:1.

[0025] Preferably, the molar ratio of the polyol to diisocyanate in step (1) is (4-10): (5.5-12), for example, 4:5.5, 4:6, 4:7, 4:8, 4:9, 4:10, 4:11, 4:12, 5:5.5, 5:6, 5:7, 5:8, 5:9, 5:10, 5:11, 5:12, 6:5.5, 6:6, 6:7, 6:8, 6:9, 6:10, 6:11, 6:12. :11, 6:12, 7:5.5, 7:6, 7:8, 7:9, 7:10, 7:11, 7:12, 8:5.5, 8:6, 8:7, 8:9, 8:10, 8:11, 8:12, 9:5.5, 9:6, 9:7, 9:8, 9:10, 9:11, 9:12, 10:5.5, 10:6, 10:7, 10:8, 10:9, 10:11 or 10:12.

[0026] Preferably, the molar ratio of the polyol to the tridentate ligand in step (1) is (4-10):1, for example, 4:1, 4.5:1, 4.8:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1 or 10:1, etc.

[0027] Preferably, the reaction in step (1) is carried out in the presence of a catalyst.

[0028] Preferably, the catalyst is dibutyltin dilaurate.

[0029] Preferably, the molar ratio of the catalyst to the polyol is (4-10):(0.2-0.5), for example, 4:0.2, 4:0.3, 4:0.4, 4:0.5, 5:0.2, 5:0.3, 5:0.4, 6:0.2, 6:0.3, 6:0.4, 6:0.5, 7:0.2, 7:0.3, 7:0.4, 7:0.5, 8:0.2, 8:0.3, 8:0.4, 8:0.5, 9:0.2, 9:0.3, 9:0.4, 9:0.5, 10:0.2, 10:0.3, 10:0.4 or 10:0.5.

[0030] Preferably, the reaction in step (1) is carried out in an organic solvent.

[0031] Preferably, the organic solvent is selected from any one of tetrahydrofuran, N,N-dimethylformamide or 1,4-dioxane, or a combination of at least two thereof.

[0032] Preferably, the molar ratio of the organic solvent to the polyol is (500-5000):(4-10), for example, 500:4, 500:6, 500:7, 500:9, 500:10, 700:4, 700:6, 700:7, 700:9, 700:10, 900:4, 900:6, 900:7, 900:9, 900:10, 1200:4, 1200:6, 1200:7, 1200:9, 00:9, 1200:10, 2000:4, 2000:6, 2000:7, 2000:9, 2000:10, 3000:4, 3000:6, 3000:7, 3000:9, 3000:10, 4000:4, 4000:6, 4000:7, 4000:9, 4000:10, 5000:4, 5000:6, 5000:7, 5000:9, or 5000:10.

[0033] Preferably, the reaction temperature in step (1) is 20-60°C (e.g., 20°C, 30°C, 40°C, 50°C, 60°C, etc.), and the reaction time is 2-12 h (e.g., 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, etc.).

[0034] Preferably, after the reaction in step (1) is completed, the solvent is removed by distillation under reduced pressure to obtain linear polyurethane.

[0035] Preferably, the reduced pressure distillation temperature is 30-50°C (e.g., 30°C, 35°C, 40°C, 45°C or 50°C), the vacuum degree is -0.090~-0.095Mpa (e.g., -0.090Mpa, -0.092Mpa, -0.095Mpa, etc.), and the reduced pressure distillation time is 0.5~2h (e.g., 0.5h, 1h, 2h, etc.).

[0036] Preferably, the divalent palladium compound in step (2) is selected from palladium acetate, palladium tetrafluoroborate, etc.

[0037] Preferably, the monodentate ligand in step (2) is selected from the following compounds:

[0038] .

[0039] Preferably, the molar ratio of the divalent palladium compound in step (2) to the tridentate ligand in step (1) is 1:1.

[0040] Preferably, the molar ratio of the monodentate ligand in step (2) to the tridentate ligand in step (1) is 1:1.

[0041] Preferably, the reaction in step (2) is carried out in an organic solvent, and the organic solvent is selected from any one or a combination of at least two of dichloromethane, N,N-dimethylformamide or acetonitrile.

[0042] Preferably, the molar ratio of the organic solvent to the monodentate ligand is (500-5000):1, for example, 500:1, 600:1, 700:1, 800:1, 1000:1, 1300:1, 1500:1, 2000:1, 2500:1, 2800:1, 3000:1, 3500:1, 4000:1, 4500:1 or 5000:1.

[0043] Preferably, the temperature of the coordination reaction in step (2) is 10-30°C (e.g., 10°C, 20°C, 30°C, etc.), and the time of the coordination reaction is 2-12 h (e.g., 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, etc.).

[0044] Preferably, the structure of the o-phenanthroline ligand in step (3) is as follows:

[0045] .

[0046] Preferably, the monovalent copper compound in step (3) includes any one of tetrakis(acetonitrile)copper tetrafluoroborate, tetrakis(acetonitrile)copper hexafluorophosphate or cuprous thiocyanate, or a combination of at least two thereof.

[0047] Preferably, the molar ratio of the o-phenanthroline ligand to the monovalent copper compound in step (3) is 2:1.

[0048] Preferably, the coordination reaction in step (3) is carried out in an organic solvent, and the organic solvent is a mixed solvent of dichloromethane and acetonitrile.

[0049] Preferably, the volume ratio of dichloromethane to acetonitrile is 1:(0.5-1.5), for example, 1:0.5, 1:0.7, 1:0.9, 1:1, 1:1.2, 1:1.4 or 1:1.5.

[0050] Preferably, the molar ratio of the organic solvent to the o-phenanthroline ligand is (500-5000):1, for example, 500:1, 700:1, 800:1, 1000:1, 1500:1, 2000:1, 2300:1, 2500:1, 2800:1, 3000:1, 3500:1, 3800:1, 4000:1, 4500:1, 4800:1 or 5000:1.

[0051] Preferably, the temperature of the coordination reaction in step (3) is 10-30°C (e.g., 10°C, 20°C, 30°C, etc.), and the time of the coordination reaction is 2-12 h (e.g., 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, etc.).

[0052] Preferably, the diprimary amine compound in step (4) is any one of p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, ethylenediamine, butanediamine or hexamethylenediamine, or a combination of at least two thereof.

[0053] Preferably, the molar ratio of the primary amine group in one of the metal coordination nodes to the primary amine group in the dibasic primary amine compound in step (4) is 1:(0-2), for example, 1:0, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.7, 1:1.9 or 1:2, etc.

[0054] Preferably, in step (4), the molar ratio of the primary amine group in one of the metal coordination nodes to the aldehyde group in the second metal coordination node is 1:(2-4), for example, 1:2, 1:2.4, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.5, 1:3.8 or 1:4, etc.

[0055] Preferably, the molar ratio of the primary amine group in one of the metal coordination nodes in step (4) to the solvent is 1:(200-2000), for example, 1:200, 1:400, 1:600, 1:800, 1:1000, 1:1300, 1:1500, 1:1800 or 1:2000.

[0056] Preferably, the solvent is a mixed solvent of dichloromethane and acetonitrile.

[0057] Preferably, the mixing temperature in step (4) is 10-30°C (e.g., 10°C, 20°C, 30°C, etc.), and the mixing time is 3-24 h (e.g., 3 h, 6 h, 9 h, 12 h, 18 h, 24 h, etc.).

[0058] Preferably, the removal of the solvent in step (4) is achieved by distillation under reduced pressure.

[0059] Preferably, the temperature of the hot pressing in step (4) is 80-150°C (for example, 80°C, 100°C, 120°C, 150°C, etc.), and the time of the hot pressing is 5 min-2 h (for example, 5 min, 10 min, 20 min, 30 min, 1 h, 2 h, etc.).

[0060] In the present invention, reversible imine bonds are used to connect the cross-metal coordination nodes to form a crystal structure that takes into account both dynamics and rigidity, and then polymerization is performed to finally obtain the degradable high-performance polyurethane material.

[0061] In the present invention, one of the metal coordination nodes has the following structure:

[0062] .

[0063] The second metal coordination node has the following structure:

[0064] .

[0065] In another aspect, the present invention provides a degradable polyurethane material prepared by the above-mentioned preparation method.

[0066] In another aspect, the present invention provides use of the above-mentioned degradable polyurethane material in an elastomeric material or an adhesive.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] The present invention connects two metal coordination nodes via reversible imine bonds to form a rigid cross-linked backbone. This rigid backbone is then used to polymerize linear polyurethane chains, forming a highly entangled polymer network with flexible segments. The movement of the flexible segments and the metal coordination nodes impart dynamics and energy dissipation to the network, while the presence of the rigid network prevents irreversible deformation of the flexible segments. This allows the composite network to retain its original shape while achieving exceptional toughness. Furthermore, the introduction of imine bonds imparts biodegradability to the network. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1The infrared absorption spectrum (FTIR) graphs of the WPU polyurethane network prepared in Example 1 and the WPU-Ph composite polymer prepared in Comparative Example 1 are shown.

[0070] Figure 2 The H NMR of the monodentate ligand ( 1 H NMR) spectrum.

[0071] Figure 3 The H NMR of the tridentate ligand ( 1 H NMR) spectrum.

[0072] Figure 4 The H NMR of the o-phenanthroline ligand ( 1 H NMR) spectrum.

[0073] Figure 5 These are stress-strain curves of the WPU polyurethane network prepared in Example 1 and the WPU-Ph composite polymer prepared in Comparative Example 1.

[0074] Figure 6 These are photos of the WPU polyurethane network prepared in Example 1 before and after degradation. DETAILED DESCRIPTION

[0075] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0076] The raw materials involved in the following examples and comparative examples are as follows:

[0077] The structure of the monodentate ligand is as follows: , its synthesis method comprises the following steps:

[0078] Dissolve 0.50 g of 2,6-bis(bromomethyl)pyridine, 0.51 g of p-hydroxybenzaldehyde, and 0.78 g of potassium carbonate in 40 mL of THF. Reflux the solution at 100°C overnight, and remove volatiles. The resulting solid is then dissolved in dichloromethane and washed several times with deionized water. The organic phase is dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain the monodentate ligand product.

[0079] Figure 2 The H NMR spectrum of the dentate ligand ( 1 1H NMR).

[0080] The structure of the tridentate ligand is as follows: , its synthesis method comprises the following steps:

[0081] Dissolve 500 mg of 2,6-pyridinedicarboxylic acid and 2.92 g of 4-dimethylaminopyridine in 80 mL of dichloromethane. Cool the resulting solution to 0°C, then add 2.87 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.64 g of p-(aminomethyl)benzyl alcohol. Stir the mixture overnight, remove volatiles, and wash the resulting organic phase with deionized water and extract with dichloromethane. Combine the organic phases, dry over anhydrous magnesium sulfate, filter, and concentrate by rotary evaporation. Purify the residue by silica gel column chromatography using a mixture of petroleum ether and ethyl acetate (2:3 by volume) as the eluent to obtain the tridentate ligand product.

[0082] Figure 3 The H NMR spectrum of the prepared tridentate ligand ( 1 1H NMR).

[0083] The structure of o-phenanthroline ligand is as follows: , its synthesis method comprises the following steps:

[0084] 1) A two-necked round-bottom flask was charged with 1.014 g of 2,9-dibromo-1,10-phenanthroline, 2.49 g of tert-butyl (4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)carbamate, 1.24 g of potassium carbonate, 347 mg of tetrakis(triphenylphosphine)palladium, 48 mL of dioxane, and 12 mL of deionized water. The reaction mixture was deoxygenated by slowly bubbling N2 for 30 minutes, then heated under reflux at 100°C for 8 hours. After cooling to room temperature, the solvent was removed under reduced pressure, and the residue was washed with deionized water and extracted with dichloromethane. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated by rotary evaporation. The residue was purified by silica gel column chromatography using a dichloromethane / methanol mixture (100:0.5, by volume) as the eluent to obtain the intermediate.

[0085] 2) Add 0.56 g of the intermediate product and 10 mL of a 4 M HCl / dioxane mixture to a round-bottom flask. Stir the mixture at room temperature for 2 h, then filter to obtain a dark red solid. Dissolve the solid in 50 mL of deionized water and neutralize with potassium hydroxide solution. Extract the suspension with dichloromethane. Combine the organic phases, wash with saturated brine, dry over anhydrous sodium sulfate, filter, and concentrate by rotary evaporation to obtain the o-phenanthroline ligand product.

[0086] Figure 4 This is the 1H NMR hydrogen spectrum of the o-phenanthroline ligand.

[0087] Polytetrahydrofuran was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0088] Example 1

[0089] This example provides a polyurethane polymer network. 0.69 g of polytetrahydrofuran, 0.01 g of butanediol, 0.03 g of HDI, and 20 mg of a tridentate ligand were mixed in 10 mL of tetrahydrofuran solvent. 0.02 g of dibutyltin dilaurate was added, and polymerization was carried out at 50°C for 3 h. After completion of polymerization, the solvent was removed by vacuum distillation. The mixture was then dissolved in 15 mL of dichloromethane. 11 mg of palladium acetate and 19 mg of a monodentate ligand were added, and the reaction was carried out at 25°C for 6 h to obtain a linear polyurethane chain with two metal coordination nodes. Separately, o-phenanthroline ligand and copper tetrakis(acetonitrile)tetrafluoroborate were added in a 2:1 molar ratio to a mixed solvent of dichloromethane:acetonitrile = 1:1. After a coordination reaction at 25°C for 6 h, the solvent was removed by vacuum distillation at 40°C and -0.095 MPa for 1 h to obtain one metal coordination node. Finally, 13 mg of one of the obtained metal coordination nodes and 2 mg of p-phenylenediamine were added to the linear polyurethane glue that formed the second metal coordination node. After mixing at 25°C for 6 hours, the solvent was removed by reduced pressure distillation at 40°C and -0.095 MPa for 1 hour. The WPU polyurethane network was then obtained by hot pressing at 120°C for 30 minutes.

[0090] Example 2

[0091] This embodiment provides a polyurethane polymer network. 0.69 g of polytetrahydrofuran, 0.01 g of butanediol, 0.03 g of HDI, and 20 mg of a tridentate ligand were mixed in 10 mL of tetrahydrofuran solvent. 0.02 g of dibutyltin dilaurate was added and polymerized at 50°C for 3 h. After completion of polymerization, the solvent was removed by vacuum distillation at 40°C and -0.095 MPa for 1 h. The mixture was then dissolved in 15 mL of dichloromethane. 11 mg of palladium acetate and 19 mg of the monodentate ligand were added and the coordination reaction was carried out at 25°C for 6 h to obtain a linear polyurethane chain with a second metal coordination node. 19 mg of one of the obtained metal coordination nodes was added to the linear polyurethane glue solution with the second metal coordination node. The mixture was mixed at 25°C for 6 h, and then the solvent was removed by vacuum distillation at 40°C and -0.095 MPa for 1 h. The WPU polyurethane network was then obtained by hot pressing at 120°C for 30 min.

[0092] Example 3

[0093] This example provides a polyurethane polymer network. 0.69 g of polytetrahydrofuran, 0.01 g of butanediol, 0.03 g of HDI, and 20 mg of a tridentate ligand were mixed in 10 mL of tetrahydrofuran solvent. 0.02 g of dibutyltin dilaurate was added and polymerized at 50°C for 3 h. After completion of polymerization, the solvent was removed by vacuum distillation at 50°C and -0.090 MPa for 1 h. The mixture was then dissolved in 15 mL of dichloromethane. 11 mg of palladium acetate and 19 mg of the monodentate ligand were added. After coordination reaction at 25°C for 6 h, a linear polyurethane chain with a second metal coordination node was obtained. 2.2 mg of one of the obtained metal coordination nodes and 4 mg of p-phenylenediamine were added to the linear polyurethane glue solution with the second metal coordination node. The mixture was mixed at 25°C for 6 h, and then the solvent was removed by vacuum distillation at 50°C and -0.090 MPa for 1 h. The WPU polyurethane network was then obtained by hot pressing at 120°C for 30 min.

[0094] Example 4

[0095] This example provides a polyurethane polymer network. 0.72 g of polytetrahydrofuran, 0.01 g of butanediol, 0.03 g of HDI, and 0.004 g of a tridentate ligand were mixed in 10 mL of tetrahydrofuran solvent, 0.02 g of dibutyltin dilaurate was added, and polymerization was carried out at 50°C for 3 h. After the polymerization, the solvent was removed by reduced pressure distillation at 30°C and -0.090 MPa for 1 h. The mixture was then dissolved in 15 mL of dichloromethane, 2.3 mg of palladium acetate and 3.7 mg of a monodentate ligand were added, and a coordination reaction was carried out at 25°C for 6 h to obtain a linear polyurethane chain with two metal coordination nodes. 2.6 mg of one of the obtained metal coordination nodes and 0.4 mg of p-phenylenediamine were added to the linear polyurethane glue that formed the second metal coordination node. After mixing at 25°C for 6 hours, the solvent was removed by reduced pressure distillation at 30°C and -0.090 MPa for 1 hour. The WPU polyurethane network was then obtained by hot pressing at 120°C for 30 minutes.

[0096] Example 5

[0097] This example provides a polyurethane polymer network. 0.34 g of polytetrahydrofuran, 0.01 g of butanediol, 0.03 g of HDI, and 20 mg of a tridentate ligand were mixed in 10 mL of tetrahydrofuran solvent. 0.02 g of dibutyltin dilaurate was added and polymerized at 50°C for 3 h. After completion of polymerization, the solvent was removed by vacuum distillation at 40°C and -0.095 MPa for 1 h. The mixture was then dissolved in 15 mL of dichloromethane. 11 mg of palladium acetate and 19 mg of the monodentate ligand were added. After coordination reaction at 25°C for 6 h, a linear polyurethane chain with a second metal coordination node was obtained. 13 mg of one of the obtained metal coordination nodes and 2 mg of p-phenylenediamine were added to the linear polyurethane glue solution with the second metal coordination node. The mixture was mixed at 25°C for 6 h, and then the solvent was removed by vacuum distillation at 40°C and -0.095 MPa for 1 h. The WPU polyurethane network was then obtained by hot pressing at 120°C for 30 min.

[0098] Comparative Example 1

[0099] This comparative example provides a polyurethane composite polymer, wherein 0.69 g of polytetrahydrofuran, 0.01 g of butanediol, 0.03 g of HDI, and 20 mg of a tridentate ligand are mixed in 10 mL of tetrahydrofuran solvent, 0.02 g of dibutyltin dilaurate is added, and polymerization is carried out at 50° C. for 3 h. After the completion of the polymerization, the mixture is subjected to reduced pressure distillation at 40° C. and −0.095 MPa for 1 h to remove the solvent, and the mixture is then dissolved in 15 mL of dichloromethane. 11 mg of palladium acetate and 15 mg of 2,6-bis(phenoxymethyl)pyridine are added, and a coordination reaction is carried out at 25° C. for 6 h to obtain a linear polyurethane chain having two metal coordination nodes. 13 mg of one of the obtained metal coordination nodes and 2 mg of p-phenylenediamine were added to the linear polyurethane glue that formed the second metal coordination node. After mixing at 25°C for 6 hours, the solvent was removed by reduced pressure distillation at 40°C and -0.095 MPa for 1 hour. The WPU-Ph composite polymer was then obtained by hot pressing at 120°C for 30 minutes.

[0100] Figure 1 The infrared absorption spectrum (FTIR) of the WPU polyurethane network prepared in Example 1 and the WPU-Ph composite polymer prepared in Comparative Example 1 shows that the 2120 cm -1 The 1640 cm-1 peak at the imine bond completely disappeared from the two polymer networks, indicating that the HDI in the system has been completely reacted. -1 The peak at is only found in the spectrum of WPU, indicating the successful construction of the rigid skeleton.

[0101] Figure 5The stress-strain curves of the WPU polyurethane network prepared in Example 1 and the WPU-Ph composite polymer prepared in Comparative Example 1 at a tensile rate of 50 mm / min are shown. It can be seen from the figure that the presence of the rigid skeleton greatly improves the mechanical properties of the polymer network.

[0102] Figure 6 These are photos of the WPU polyurethane network prepared in Example 1 before and after degradation in a dilute hydrochloric acid / tetrahydrofuran solution. From the figure, it can be seen that the originally strong polymer network can be quickly and completely degraded in a dilute acid environment, proving its excellent degradability.

[0103] Performance testing:

[0104] Tensile strength: tested using GB / T 528-2009 method.

[0105] Elongation at break: tested using GB / T 528-2009 method.

[0106] Toughness: tested using GB / T 7124-2008 method.

[0107] Recovery rate: tested using GB / T2794 method.

[0108] Table 1

[0109]

[0110] According to the data in Table 1, taking Examples 1-5 as an example, the toughness of the polyurethane network of the present invention is 69~1824MJ / m 3 , tensile strength is 33~115 MPa, elongation at break is 380~3440%, and recovery rate is 70~83%.

[0111] Analysis of Comparative Example 1 and Example 1 shows that Comparative Example 1 uses 2,6-bis(phenoxymethyl)pyridine instead of a monodentate ligand to coordinate palladium ions, making it difficult to form an imine bond with one of the metal coordination nodes, resulting in difficulty in forming a rigid cross-linked skeleton inside. Compared with Example 1, the tensile strength of the system decreased from 115 MPa to 10.4 MPa, the elongation at break decreased from 3440% to 288%, and the toughness decreased from 1824 MJ / m 3 Down to 28.9 MJ / m 3 , the recovery rate dropped from 78% to 69%. This shows that integrating a rigid cross-linked skeleton with flexible polymer chains can greatly improve the mechanical properties of polymer materials.

[0112] Analysis of Examples 1-3 shows that adding an appropriate amount of one of the metal coordination nodes controls the crosslink density of the rigid backbone network. Excessive addition of one of the metal coordination nodes results in an excessively high crosslink density, hindering the dynamic nature of the nodes and energy dissipation. Conversely, a low crosslink density makes it difficult for the network to crosslink and form a stable whole. An appropriate crosslink density balances energy dissipation and structural stability.

[0113] Analysis of Examples 1, 4, and 5 shows that controlling the content of the second metal coordination nodes in the polymer network can control the crosslink density of the rigid backbone network. Too few second metal coordination nodes reduce the interaction between the rigid backbone and the polymer chains, making them difficult to integrate; too many nodes increase the rigidity of the polymer chains and lead to increased network brittleness. An appropriate node content will help produce polymer network samples with better performance.

[0114] While the present invention is illustrated by the above-described embodiments, the present invention is not limited to the above-described process steps, and implementation of the present invention is not necessarily dependent on the above-described process steps. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a degradable polyurethane material, characterized in that: The preparation method comprises the following steps: (1) Polyol, small molecule chain extender, diisocyanate and tridentate ligand react to obtain linear polyurethane; (2) the linear polyurethane obtained in step (1) undergoes a coordination reaction with a divalent palladium compound and a monodentate ligand to obtain a polyurethane solution containing two metal coordination nodes; (3) The o-phenanthroline ligand undergoes a coordination reaction with a monovalent copper compound to obtain a solution containing one of the metal coordination nodes; (4) mixing the solution containing one of the metal coordination nodes obtained in step (3) with the optional diprimary amine compound and the polyurethane solution containing the second metal coordination node obtained in step (2), removing the solvent, and hot pressing to obtain the degradable polyurethane material; The tridentate ligand in step (1) is the following compound: ； The monodentate ligand in step (2) is selected from the following compounds: ； The structure of the o-phenanthroline ligand in step (3) is as follows: 。 2. The method for preparing a degradable polyurethane material according to claim 1, wherein: The polyol is selected from polyols terminated with hydroxyl groups at both ends.

3. The method for preparing a degradable polyurethane material according to claim 1, wherein: The polyol is selected from any one of polytetrahydrofuran, polyethylene glycol or polypropylene glycol, or a combination of at least two thereof; The number average molecular weight of the polyol is 400-4000 g / mol; The small molecule chain extender is a small molecule diol, and the small molecule diol includes any one of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or 4-phenylenediol, or a combination of at least two thereof.

4. The method for preparing a degradable polyurethane material according to claim 1, wherein: The diisocyanate is selected from any one of hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate and dicyclohexylmethane-4,4'-diisocyanate, or a combination of at least two thereof.

5. The method for preparing a degradable polyurethane material according to claim 1, wherein: The molar ratio of the polyol to the small molecule chain extender in step (1) is (4-10): (0.4-1); The molar ratio of the polyol to diisocyanate in step (1) is (4-10): (5.5-12); The molar ratio of the polyol to the tridentate ligand in step (1) is (4-10):

1.

6. The method for preparing a degradable polyurethane material according to claim 1, wherein: The reaction in step (1) is carried out in the presence of a catalyst; The catalyst is dibutyltin dilaurate; The molar ratio of the catalyst to the polyol is (4-10): (0.2-0.5).

7. The method for preparing a degradable polyurethane material according to claim 1, wherein: The reaction in step (1) is carried out in an organic solvent; The organic solvent is selected from any one or a combination of at least two of tetrahydrofuran, N,N-dimethylformamide or 1,4-dioxane; The molar ratio of the organic solvent to the polyol is (500-5000): (4-10); The reaction temperature in step (1) is 20-60°C, and the reaction time is 2-12 h; After the reaction in step (1) is completed, the solvent is removed by distillation under reduced pressure to obtain a linear polyurethane; The reduced pressure distillation temperature is 30-50° C., the vacuum degree is -0.090 to -0.095 MPa, and the reduced pressure distillation time is 0.5 to 2 h.

8. The method for preparing a degradable polyurethane material according to claim 1, wherein: The divalent palladium compound in step (2) is selected from palladium acetate or palladium tetrafluoroborate; The molar ratio of the divalent palladium compound in step (2) to the tridentate ligand in step (1) is 1:1; The molar ratio of the monodentate ligand in step (2) to the tridentate ligand in step (1) is 1:1; The reaction in step (2) is carried out in an organic solvent, wherein the organic solvent is selected from any one or a combination of at least two of dichloromethane, N,N-dimethylformamide or acetonitrile; The molar ratio of the organic solvent to the monodentate ligand is (500-5000):1; The temperature of the coordination reaction in step (2) is 10-30°C, and the time of the coordination reaction is 2-12 hours; The monovalent copper compound in step (3) includes any one of tetra(acetonitrile)copper tetrafluoroborate, tetra(acetonitrile)copper hexafluorophosphate or cuprous thiocyanate, or a combination of at least two thereof; The molar ratio of the o-phenanthroline ligand to the monovalent copper compound in step (3) is 2:1; The coordination reaction in step (3) is carried out in an organic solvent, which is a mixed solvent of dichloromethane and acetonitrile; The volume ratio of dichloromethane to acetonitrile is 1: (0.5-1.5); The molar ratio of the organic solvent to the o-phenanthroline ligand is (500-5000):1; The temperature of the coordination reaction in step (3) is 10-30°C, and the time of the coordination reaction is 2-12 hours; The diprimary amine compound in step (4) is any one of p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, ethylenediamine, butanediamine or hexamethylenediamine, or a combination of at least two thereof; The molar ratio of the primary amine group in one of the metal coordination nodes to the primary amine group in the dibasic primary amine compound in step (4) is 1:(0-2); In step (4), the molar ratio of the primary amine group in one of the metal coordination nodes to the aldehyde group in the second metal coordination node is 1:(2-4); The molar ratio of the primary amine group in one of the metal coordination nodes to the solvent in step (4) is 1:(200-2000); The solvent is a mixed solvent of dichloromethane and acetonitrile; The mixing temperature in step (4) is 10-30° C., and the mixing time is 3-24 h; The removal of the solvent in step (4) is achieved by vacuum distillation; The hot pressing temperature in step (4) is 80-150° C., and the hot pressing time is 5 min-2 h.

9. The degradable polyurethane material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the degradable polyurethane material according to claim 9 in elastomeric materials or adhesives.

Images