Waterborne polyurethane elastomer capable of efficiently self-repairing at room temperature as well as preparation method and application of waterborne polyurethane elastomer

Abstract

The invention belongs to the technical field of high polymer materials, and discloses a waterborne polyurethane elastomer capable of efficiently self-repairing at room temperature as well as a preparation method and application of the waterborne polyurethane elastomer. The waterborne polyurethane elastomer comprises a cationic waterborne polyurethane prepolymer molecular chain of a diketone ligand group. The thermal excitation temperature needed by self-repairing of the waterborne polyurethane elastomer is low, repairing can be achieved at the room temperature, the repairing time is short, and the repairing efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a room temperature efficient self-repairing waterborne polyurethane elastomer and a preparation method and application thereof. Background Art

[0002] The development of new functional materials is often inspired by some novel inspirations in nature. Current material science has made remarkable achievements in the field of bionic materials. For example, inspired by the characteristics of lotus leaves that remain unstained in mud and dripping water without getting sticky, researchers have prepared antifouling hydrophobic materials and coatings; inspired by the gecko's crawling on the wall, humans have made bionic gecko adhesive materials. The self-healing ability of polymers is also inspired by organisms in nature, and has attracted widespread attention since its launch.

[0003] There are many methods for preparing self-healing materials. Using dynamic reversible covalent bonds and non-covalent bonds to achieve the self-healing ability of materials is the two mainstream methods currently being studied. Intermolecular interactions in supramolecular chemistry, as a typical form of dynamic reversible non-covalent interactions, are an effective strategy to give polymer materials biomimetic self-healing capabilities and new functions. Self-healing properties can enhance the reliability and service life of materials, save costs, and reduce the waste of non-renewable resources such as petrochemicals and the corresponding plastic pollution.

[0004] However, most of the intrinsic self-healing polymer materials reported so far require the help of external energy or material stimulation to trigger the repair process, such as heat, light, initiators, solvents, etc. Photoresponsive self-healing materials are usually produced by introducing groups that can trigger photoreactions into polymers. This type of material can complete the wound recovery by simply exposing the damaged material to light conditions. Its advantages are very prominent, and its disadvantages are also obvious. For cases with poor transparency and thick materials, this type of solution does not perform very well. In contrast, the thermal responsive self-healing strategy has strong material universality and is not affected by material morphology and size. More importantly, this strategy can achieve high-efficiency repair results with strong reliability. Thermal responsive self-healing is the most studied type of repair at present. However. Most of the thermal responsive self-healing materials reported so far generally require high repair temperatures and long repair times.

[0005] Therefore, there is an urgent need to provide a new self-healing material, which has a low thermal excitation temperature required for self-repair, a short repair time and a high repair efficiency. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a room temperature efficient self-repairing waterborne polyurethane elastomer and its preparation method and application. The waterborne polyurethane elastomer of the present invention has a low thermal excitation temperature required for self-repair, can be repaired at room temperature, has a short repair time and high repair efficiency.

[0007] The waterborne polyurethane elastomer provided by the present invention can achieve efficient self-repair at room temperature and has low-temperature repairability. Maleic dihydrazide (MDA) molecules rich in diketone structure are introduced into cationic waterborne polyurethane prepolymer molecular chains with N-methyldiethanolamine (MEDA) as hydrophilic groups by step-by-step polymerization to modify them. Subsequently, the polyurethane prepolymer containing diketone ligand groups is further reacted with lanthanide metal ions europium (III) (Eu 3+ ) to coordinate cross-linking and build a dynamic and reversible non-covalent cross-linking network between polymer chains. By controlling the amount of the introduced coordination cross-linking network, a controllable Eu 3+ Waterborne polyurethane elastomer toughened by ionic coordination bonds. Waterborne polyurethane elastomer exhibits typical elastomer behavior, with a tensile strength of up to 17.78MPa and an elongation at break of up to 2050%. Regulating the construction of the coordination cross-linking network can give waterborne polyurethane elastomers efficient self-repairing ability at room temperature and outstanding low-temperature repairability, and can give them reprocessability and shape memory functions.

[0008] The first aspect of the present invention provides a room temperature highly efficient self-healing waterborne polyurethane elastomer.

[0009] Specifically, a room temperature efficient self-healing waterborne polyurethane elastomer includes a cationic waterborne polyurethane prepolymer molecular chain with a diketone ligand group.

[0010] Preferably, the waterborne polyurethane elastomer further comprises Eu 3+ .

[0011] Preferably, the diketone ligand group is provided by maleic acid dihydrazide.

[0012] Preferably, the hydrophilic groups in the molecular chain of the cationic waterborne polyurethane prepolymer are provided by N-methyldiethanolamine.

[0013] Preferably, the tensile strength of the waterborne polyurethane elastomer is not less than 6 MPa, and more preferably not less than 10 MPa.

[0014] Preferably, the elongation at break of the waterborne polyurethane elastomer is not less than 1900%, and more preferably not less than 2000%.

[0015] The second aspect of the present invention provides a method for preparing a room temperature efficient self-healing waterborne polyurethane elastomer.

[0016] Specifically, a method for preparing a room temperature efficient self-repairing waterborne polyurethane elastomer comprises the following steps:

[0017] (1) mixing isocyanate, polyether alcohol, N-methyldiethanolamine, and an organic solvent, adding a catalyst, and carrying out a first reaction under a protective gas atmosphere to obtain a substance a, then adding a substance containing a diketone ligand group, carrying out a second reaction, and then adding an acid, carrying out a third reaction, and obtaining a waterborne polyurethane elastomer prepolymer;

[0018] (2) adding ice water to the waterborne polyurethane elastomer prepolymer for emulsification to obtain a waterborne polyurethane elastomer aqueous emulsion, and curing to obtain the waterborne polyurethane elastomer.

[0019] Preferably, after the third reaction is completed, an organic substance containing europium is added to carry out a fourth reaction.

[0020] Preferably, the molar ratio of the isocyanate, the polyether alcohol and the N-methyldiethanolamine is 25.54-30.14:10:(11-15), and more preferably 25.54-30.14:10:13.16.

[0021] Preferably, the usage ratio of the polyether alcohol to the organic solvent is 10 mmol:(40-60) mL, and more preferably 10 mmol:(45-50) mL.

[0022] Preferably, the isocyanate includes at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate, and hexamethylene diisocyanate (HDI), and more preferably hexamethylene diisocyanate (HDI).

[0023] Preferably, the polyether alcohol comprises polytetramethylene ether glycol (PTMG).

[0024] Preferably, the organic solvent comprises acetone.

[0025] Preferably, the usage ratio of the catalyst to the polyether alcohol is 0.02-0.05 g:10 mmol, more preferably 0.03-0.04 g:10 mmol.

[0026] Preferably, the catalyst comprises an organic tin catalyst, more preferably dibutyltin dilaurate (DBTDL).

[0027] Preferably, the protective gas includes nitrogen or a rare gas, such as argon or helium.

[0028] Preferably, the temperature of the first reaction is 60-65° C., and the time of the first reaction is 1-3 hours. More preferably, the temperature of the first reaction is 62-65° C., and the time of the first reaction is 2-3 hours.

[0029] Preferably, the usage ratio of the polyether alcohol to the substance containing a diketone ligand group is 10 mmol:(2.0-7.5) mmol, and more preferably 10 mmol:(2.38-6.98) mmol.

[0030] Preferably, the substance containing a diketone ligand group comprises maleic dihydrazide (MDA).

[0031] Preferably, the temperature of the second reaction is 55-60° C., and the time of the second reaction is 4-6 hours. More preferably, the temperature of the second reaction is 58-60° C., and the time of the second reaction is 5-6 hours.

[0032] Preferably, the ratio of the polyether alcohol to the acid is 10 mmol:(11-15) mmol, more preferably 10 mmol:(12-13.66) mmol.

[0033] Preferably, the acid comprises glacial acetic acid.

[0034] Preferably, the temperature of the third reaction is 15-35° C., and the time of the third reaction is 0.1-0.5 hour. More preferably, the temperature of the third reaction is 25-35° C., and the time of the third reaction is 0.2-0.5 hour.

[0035] Preferably, the usage ratio of the polyether alcohol to the europium organic matter is 10 mmol:(0.5-2.5) mmol, and more preferably 10 mmol:(0.79-2.32) mmol.

[0036] Preferably, the organic europium compound includes europium trifluoromethanesulfonate (Eu(CF3SO3)3).

[0037] Preferably, the temperature of the fourth reaction is 35-43° C., and the time of the fourth reaction is 12-24 hours. More preferably, the temperature of the fourth reaction is 40-43° C., and the time of the fourth reaction is 18-24 hours.

[0038] Preferably, the ice water is deionized ice.

[0039] Preferably, the curing time is 8-12 hours, more preferably 10-12 hours. The curing temperature is room temperature.

[0040] Preferably, the preparation method comprises the following steps:

[0041] (1) Polytetramethylene glycol (PTMG) and N-methyldiethanolamine (MEDA) were dried under vacuum at 100-110°C for 3 h before use;

[0042] (2) Hexamethylene diisocyanate (HDI), PTMG and MEDA were dissolved in 40-50 mL of acetone, placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer, and dibutyltin dilaurate (DBTDL) catalyst was added, and the mixture was reacted at 60-65° C. for 2-3 h under a nitrogen atmosphere;

[0043] (3) Cooling the reaction temperature of step (2) to below 55° C., adding maleic acid dihydrazide (MDA), and continuing the reaction at 55-60° C. for 4-6 hours;

[0044] (4) lowering the system temperature after the reaction in step (3) to below 35° C., neutralizing the tertiary amine group of the MEDA unit on the prepolymer chain with a slightly excess amount of glacial acetic acid (AcOH), and reacting for 20-30 min. Subsequently, slowly dropping an acetone solution of europium trifluoromethanesulfonate (Eu(CF3SO3)3) into the above prepolymer solution, and reacting at 42-43° C. for 20-24 h to obtain an acetone solution of a waterborne polyurethane elastomer prepolymer;

[0045] (5) After the reaction in step (4) is completed, the temperature of the system is lowered to room temperature. If the viscosity of the system is high, acetone solvent is added to adjust the viscosity so as to facilitate the phase inversion emulsification in the next step. Finally, ice deionized water is uniformly added to the system while performing high-speed shear dispersion emulsification. The resulting mixture is allowed to stand at room temperature overnight.

[0046] (6) removing excess acetone from the system obtained in step (5) under reduced pressure at a temperature not higher than 40° C. to obtain a uniform and stable aqueous polyurethane elastomer aqueous emulsion, and curing the aqueous polyurethane elastomer.

[0047] The third aspect of the present invention provides an application of a room temperature efficient self-healing waterborne polyurethane elastomer.

[0048] The above waterborne polyurethane elastomer is used in the fields of automobiles, construction, aerospace, instruments or sports equipment.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] The present invention utilizes MDA containing diketone coordination units to carry out functional chemical modification on cationic waterborne polyurethane molecular chains, and introduces free lanthanide coordination metal ions Eu into the system. 3+ The electron-rich diketone structure can be charged by the electron-deficient Eu 3+ Ion capture spontaneously forms a strong coordination bond, an Eu3+ Ions can capture three diketone structural units to form an effective dynamic reversible cross-linked network structure between polymer molecular chains. By adjusting the amount of ligands and coordinated metals introduced, the balance between intermolecular forces and chain mobility can be regulated, thereby preparing waterborne polyurethane elastomers with excellent mechanical properties, flexibility, thermal stability and dynamic viscoelastic behavior. The tensile strength of waterborne polyurethane elastomers can exceed 6MPa, and the elongation at break can exceed 2000%. The construction of a strong dynamic reversible cross-linked network gives waterborne polyurethane elastomers efficient bionic self-repairing ability at room temperature and outstanding low-temperature repairability, and also makes them reprocessable and shape memory. The waterborne polyurethane elastomer with fracture damage can achieve a fracture self-repair efficiency of 98.5% after repair at room temperature for 24 hours, and its strength after repair is still as high as 6.06MPa, and its elongation at break is as high as 2105.56%. It is worth noting that it can still show fracture repair efficiencies of up to 76.94% and 51.07% at 0℃ and -30℃, respectively. Moreover, the repaired waterborne polyurethane elastomer can withstand multiple cyclic stretching and exhibit good elastic behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The synthetic flow chart of WPU-MEu1 aqueous emulsion in Example 1 of the present invention;

[0052] Figure 2 The infrared spectra of the waterborne polyurethane elastomer prepared in Example 2 are as follows;

[0053] Figure 3 The local infrared spectra of the waterborne polyurethane elastomer prepared in Example 2 are as follows;

[0054] Figure 4 It is a self-healing performance diagram of the waterborne polyurethane elastomer prepared in the examples and comparative examples;

[0055] Figure 5 This is a diagram showing the shape memory function of WPU-MEu1 after being repaired at room temperature and loading a 2kg weight. DETAILED DESCRIPTION

[0056] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0057] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0058] Example 1

[0059] A method for preparing a room temperature efficient self-repairing waterborne polyurethane elastomer comprises the following steps:

[0060] First, 25.54mmol HDI (hexamethylene diisocyanate), 10mmol PTMG (polytetramethylene ether glycol) and 13.16mmol MEDA (N-methyldiethanolamine) were dissolved in 50mL acetone and placed in a 500mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (about 0.04g) were added, and the mixture was reacted at 65°C for 3h under a nitrogen atmosphere. The obtained mixture was then cooled to below 55°C, 2.38mmol MDA (maleic acid dihydrazide) was added to the mixture, and the reaction was continued at 60°C for 6h. Subsequently, the system temperature was lowered to below 35°C, and the tertiary amine group of the MEDA unit on the prepolymer chain was neutralized with a slight excess of 13.66mmol AcOH. The reaction was carried out for 30min to obtain a prepolymer solution, and then 0.79mmol The acetone solution of Eu(CF3SO3)3 was slowly added to the prepolymer solution, and the mixture was reacted at 43°C for 24 hours to obtain an acetone solution of an aqueous polyurethane elastomer prepolymer. After the reaction, the system temperature was lowered to room temperature. Finally, ice deionized water was uniformly added to the aqueous polyurethane elastomer prepolymer acetone solution, and high-speed shear dispersion was performed for emulsification. The obtained mixture was allowed to stand at room temperature overnight, and excess acetone in the system was evaporated under reduced pressure at not higher than 40°C to obtain a uniform and stable WPU-MEu1 aqueous emulsion. The WPU-MEu1 aqueous emulsion was poured into a silicone mold, and allowed to stand on a horizontal surface at room temperature for 12 hours to evaporate the moisture and solidify, and then placed in a blast oven at 60°C for 48 hours to obtain an aqueous polyurethane elastomer (denoted as WPU-MEu1).

[0061] Example 2

[0062] A method for preparing a room temperature efficient self-repairing waterborne polyurethane elastomer comprises the following steps:

[0063] First, 27.78mmol HDI (hexamethylene diisocyanate), 10mmol PTMG (polytetramethylene ether glycol) and 13.16mmol MEDA (N-methyldiethanolamine) were dissolved in 50mL acetone and placed in a 500mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (about 0.04g) were added, and the mixture was reacted at 65°C for 3h under a nitrogen atmosphere. The obtained mixture was then cooled to below 55°C, 4.62mmol MDA (maleic acid dihydrazide) was added to the mixture, and the reaction was continued at 60°C for 6h. Subsequently, the system temperature was lowered to below 35°C, and a slight excess of 13.66mmol AcOH was used to neutralize the tertiary amine group of the MEDA unit on the prepolymer chain. The reaction was carried out for 30min to obtain a prepolymer solution, and then 1.54mmol The acetone solution of Eu(CF3SO3)3 was slowly added to the prepolymer solution, and the reaction was carried out at 43°C for 24 hours to obtain an acetone solution of a waterborne polyurethane elastomer prepolymer. After the reaction, the system temperature was lowered to room temperature. Finally, ice deionized water was uniformly added to the waterborne polyurethane elastomer prepolymer acetone solution, and high-speed shear dispersion was performed for emulsification. The obtained mixture was allowed to stand at room temperature overnight, and excess acetone in the system was evaporated under reduced pressure at not higher than 40°C to obtain a uniform and stable WPU-MEu2 aqueous emulsion. The WPU-MEu2 aqueous emulsion was poured into a silicone mold, and allowed to stand on a horizontal surface at room temperature for 12 hours to evaporate the moisture and solidify, and then placed in a blast oven at 60°C for 48 hours to obtain a waterborne polyurethane elastomer (denoted as WPU-MEu2).

[0064] Example 3

[0065] A method for preparing a room temperature efficient self-repairing waterborne polyurethane elastomer comprises the following steps:

[0066] First, 30.14mmol HDI (hexamethylene diisocyanate), 10mmol PTMG (polytetramethylene ether glycol) and 13.16mmol MEDA (N-methyldiethanolamine) were dissolved in 50mL acetone and placed in a 500mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (about 0.04g) were added, and the mixture was reacted at 65°C for 3h under a nitrogen atmosphere. The obtained mixture was then cooled to below 55°C, 6.98mmol MDA (maleic acid dihydrazide) was added to the mixture, and the reaction was continued at 60°C for 6h. Subsequently, the system temperature was lowered to below 35°C, and a slight excess of 13.66mmol AcOH was used to neutralize the tertiary amine group of the MEDA unit on the prepolymer chain. The reaction was carried out for 30min to obtain a prepolymer solution, and then 2.32mmol The acetone solution of Eu(CF3SO3)3 was slowly added to the prepolymer solution, and the reaction was carried out at 43°C for 24 hours to obtain an acetone solution of a waterborne polyurethane elastomer prepolymer. After the reaction, the system temperature was lowered to room temperature. Finally, ice deionized water was uniformly added to the acetone solution of the waterborne polyurethane elastomer prepolymer, and high-speed shear dispersion was performed for emulsification. The obtained mixture was allowed to stand at room temperature overnight, and excess acetone in the system was evaporated under reduced pressure at not higher than 40°C to obtain a uniform and stable WPU-MEu3 aqueous emulsion. The WPU-MEu3 aqueous emulsion was poured into a silicone mold, and allowed to stand on a horizontal surface at room temperature for 12 hours to evaporate the moisture and solidify, and then placed in a blast oven at 60°C for 48 hours to obtain a waterborne polyurethane elastomer (denoted as WPU-MEu3).

[0067] Example 4

[0068] A method for preparing a waterborne polyurethane elastomer comprises the following steps:

[0069] First, 25.54mmol HDI (hexamethylene diisocyanate), 10mmol PTMG (polytetramethylene ether glycol) and 13.16mmol MEDA (N-methyldiethanolamine) were dissolved in 50mL acetone and placed in a 500mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (about 0.04g) were added, and the mixture was reacted at 65°C for 3h under a nitrogen atmosphere. The temperature of the obtained mixture was then cooled to below 55°C, and 2.38mmol MDA (maleic acid dihydrazide) was added to the mixture. The reaction was continued at 60°C for 6h. Subsequently, the system temperature was lowered to below 35°C, and a slight excess of 13.66mmol AcOH neutralizes the tertiary amine group of the MEDA unit on the prepolymer chain, reacts for 30 minutes, and obtains a prepolymer solution. The system temperature is lowered to room temperature. Finally, ice deionized water is uniformly added to the prepolymer solution, and high-speed shear dispersion is performed for emulsification. The obtained mixture is allowed to stand at room temperature overnight, and excess acetone in the system is evaporated under reduced pressure at no more than 40°C to obtain a uniform and stable WPU-M aqueous emulsion. The WPU-M aqueous emulsion is poured into a silicone mold, and allowed to stand on a horizontal platform at room temperature for 12 hours to evaporate moisture and solidify, and then placed in a blast oven at 60°C for 48 hours to obtain a waterborne polyurethane elastomer (denoted as WPU-M).

[0070] Comparative Example 1

[0071] A method for preparing a waterborne polyurethane elastomer comprises the following steps:

[0072] First, 25.54mmol HDI (hexamethylene diisocyanate), 10mmol PTMG (polytetramethylene ether glycol) and 13.16mmol MEDA (N-methyldiethanolamine) were dissolved in 50mL acetone and placed in a 500mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (about 0.04g) were added and reacted at 65°C for 3h under a nitrogen atmosphere. Subsequently, the system temperature was lowered to below 35°C, and a slight excess of 13.66mmol AcOH was used to neutralize the tertiary amine group of the MEDA unit on the prepolymer chain. The reaction was carried out for 30min to obtain a prepolymer solution. Then, 0.79mmol The acetone solution of Eu(CF3SO3)3 was slowly added to the prepolymer solution, and the reaction was carried out at 43°C for 24 hours to obtain the prepolymer acetone solution. After the reaction was completed, the system temperature was lowered to room temperature. Finally, ice deionized water was uniformly added to the prepolymer acetone solution, and high-speed shear dispersion was performed for emulsification. The obtained mixture was allowed to stand at room temperature overnight, and the excess acetone in the system was evaporated under reduced pressure at not higher than 40°C to obtain a uniform and stable WPU+Eu aqueous emulsion. The WPU+Eu aqueous emulsion was poured into a silicone mold, and allowed to stand on a horizontal surface at room temperature for 12 hours to evaporate the moisture and solidify, and then placed in a blast oven at 60°C for 48 hours to obtain a waterborne polyurethane elastomer (denoted as WPU+Eu).

[0073] Comparative Example 2

[0074] A method for preparing a waterborne polyurethane elastomer comprises the following steps:

[0075] First, 25.54mmol HDI (hexamethylene diisocyanate), 10mmol PTMG (polytetramethylene ether glycol) and 13.16mmol MEDA (N-methyldiethanolamine) were dissolved in 50mL acetone and placed in a 500mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (about 0.04g) were added. The reaction was carried out at 65°C for 3h under a nitrogen atmosphere. The system temperature was lowered to below 35°C and a slight excess of 13.66mmol AcOH neutralizes the tertiary amine group of the MEDA unit on the prepolymer chain and reacts for 30 minutes. After the reaction, the system temperature is lowered to room temperature, ice deionized water is added at a uniform rate, and high-speed shear dispersion is performed for emulsification. The obtained mixture is allowed to stand at room temperature overnight, and excess acetone in the system is evaporated under reduced pressure at no higher than 40°C to obtain a uniform and stable WPU aqueous emulsion. The WPU aqueous emulsion is poured into a silicone mold, and allowed to stand on a horizontal surface at room temperature for 12 hours to evaporate moisture and solidify, and then placed in a blast oven at 60°C for 48 hours to obtain a waterborne polyurethane elastomer (referred to as WPU).

[0076] Product effect testing

[0077] Figure 1 This is a synthesis flow chart of the WPU-MEu1 aqueous emulsion in Example 1 of the present invention. Figure 2 The infrared spectra of the waterborne polyurethane elastomer prepared in Example 2 are as follows; Figure 3 This is a partial infrared spectrum of the waterborne polyurethane elastomer prepared in Example 2. Figure 2 and Figure 3 The “Wavenumber” in the figure indicates the wave number, and the “Transmittance” indicates the wave number. The functional groups of the samples were tested using a TENSOR27 Fourier transform infrared spectrometer (Bruker, Germany) in ATR mode (total reflection attenuation mode) with a scanning range of 4000–500 cm -1 .

[0078] The waterborne polyurethane elastomer (in the form of a film) prepared in the above examples and comparative examples was tested for self-healing properties. The results are as follows: Figure 4 shown.

[0079] The self-healing performance is mainly evaluated by the degree of recovery of the mechanical strength of the sample within a set time. First, the sample film is cut into two pieces and reassembled. Then, the sample is allowed to complete self-healing under different time and temperature conditions, and the degree of recovery of its mechanical properties is evaluated.

[0080] The self-healing efficiency (η) is calculated by the ratio of the tensile strength (σ) of the repaired sample to the original tensile strength (σ0) of the sample, and the formula is as follows: η = σ / σ0*100%.

[0081] Figure 4 It is a self-healing performance diagram of the waterborne polyurethane elastomer prepared in the examples and comparative examples; Figure 4 In the figure, the stress-strain curves of WPU, WPU-M, WPU-MEu2 and WPU-MEu3 after self-healing for a certain period of time at room temperature, 0℃ and -30℃ (corresponding to Figures (a), (b), (c), (g) respectively) and self-healing efficiency (corresponding to Figures (d), (e), (f), (j) respectively). The stress-strain curves of WPU-MEu1 after self-healing for different lengths of time at room temperature (corresponding to Figure (h)) and self-healing efficiency (corresponding to Figure (k)), and its stress-strain curves after 4 days of repair at 0℃ and -30℃ (corresponding to Figure (i)), and the cyclic stress-strain curve of WPU-MEu1 after 48h of fracture self-healing at room temperature (corresponding to Figure (l)). Figure 4“Original” here means the original water-based polyurethane elastomer, “D” means day, “Stress” means stress, “Strain” means strain, “Healing Efficiency” means self-healing efficiency, and “1st cycle”, “2nd cycle”, “3rd cycle”, “4th cycle”, “5th cycle”, “6th cycle”, “7th cycle”, “8th cycle”, “9th cycle”, “10th cycle”, and “once” means the 1st cycle, 2nd cycle, 3rd cycle, 4th cycle, 5th cycle, 6th cycle, 7th cycle, 8th cycle, 9th cycle, and 10th cycle. Figure 4 It can be seen that the waterborne polyurethane elastomer prepared in the embodiment of the present invention also has a good room temperature repair effect, especially high strength after self-repair.

[0082] Figure 5 This is a diagram showing the shape memory function of WPU-MEu1 after being repaired at room temperature and loading a 2kg weight. Figure 5 (“cut” means cutting short) Figure (a) corresponds to the display result with a load of 2 kg, and Figure (b) corresponds to the demonstration result of the shape memory function.

[0083] Figure 5 The results of the load demonstration of the WPU-MEu1 specimen after room temperature repair are shown. The narrow part of the dumbbell-shaped WPU-MEu1 specimen with a length of 35 mm is 2 mm wide and 0.62 mm thick. After folding it in half, two 1000 g weights are hung on its fracture. The specimen can effectively lift a 2000 g weight, indicating that WPU-MEu1 has excellent self-healing ability and mechanical properties ( Figure 5 In addition, the stretched and yielded spline can quickly recover to its original shape and size in a 50℃ thermal environment ( Figure 5 (b) in the figure indicates that the prepared waterborne polyurethane elastomer also has shape memory function.

Claims

1. A waterborne polyurethane elastomer, characterized in that: A cationic waterborne polyurethane prepolymer molecular chain including a diketone ligand group.

2. The waterborne polyurethane elastomer according to claim 1, characterized in that The waterborne polyurethane elastomer further comprises Eu 3+ ; and / or, the diketone ligand group is provided by maleic acid dihydrazide.

3. The waterborne polyurethane elastomer according to claim 1, characterized in that The hydrophilic groups in the molecular chain of the cationic waterborne polyurethane prepolymer are provided by N-methyldiethanolamine.

4. The waterborne polyurethane elastomer according to claim 2, characterized in that: The tensile strength of the waterborne polyurethane elastomer is not less than 6 MPa; and / or the elongation at break of the waterborne polyurethane elastomer is not less than 1900%.

5. The method for preparing the waterborne polyurethane elastomer according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) mixing isocyanate, polyether alcohol, N-methyldiethanolamine, and an organic solvent, adding a catalyst, and carrying out a first reaction under a protective gas atmosphere to obtain a substance a, then adding a substance containing a diketone ligand group, carrying out a second reaction, and then adding an acid, carrying out a third reaction, and obtaining a waterborne polyurethane elastomer prepolymer; (2) adding ice water to the waterborne polyurethane elastomer prepolymer for emulsification to obtain a waterborne polyurethane elastomer aqueous emulsion, and curing to obtain the waterborne polyurethane elastomer.

6. The preparation method according to claim 5, characterized in that: After the third reaction is completed, an organic substance containing europium is added to carry out a fourth reaction; and / or the molar ratio of the isocyanate, the polyether alcohol and the N-methyldiethanolamine is 25.54-30.14:10:(11-15); and / or the amount ratio of the polyether alcohol to the organic solvent is 10mmol:(40-60)mL.

7. The preparation method according to claim 5, characterized in that: The polyether alcohol comprises polytetrahydrofuran ether glycol; and / or, the usage ratio of the catalyst to the polyether alcohol is 0.02-0.05 g:10 mmol; and / or, the catalyst comprises an organic tin catalyst.

8. The preparation method according to claim 5, characterized in that: The temperature of the first reaction is 60-65° C., and the time of the first reaction is 1-3 hours; and / or, the dosage ratio of the polyether alcohol to the substance containing a diketone ligand group is 10 mmol:(2.0-7.5) mmol; and / or, the substance containing a diketone ligand group includes maleic acid dihydrazide.

9. The preparation method according to claim 6, characterized in that: The temperature of the second reaction is 55-60°C, and the time of the second reaction is 4-6 hours; and / or, the dosage ratio of the polyether alcohol to the acid is 10mmol:(11-15)mmol; and / or, the acid includes glacial acetic acid; and / or, the temperature of the third reaction is 15-35°C, and the time of the third reaction is 0.1-0.5 hour; and / or, the dosage ratio of the polyether alcohol to the europium organic matter is 10mmol:(0.5-2.5)mmol; and / or, the europium organic matter includes europium trifluoromethanesulfonate; and / or, the temperature of the fourth reaction is 35-43°C, and the time of the fourth reaction is 12-24 hours.

10. Use of the waterborne polyurethane elastomer according to any one of claims 1 to 4 in the fields of automobiles, construction, aerospace, instruments or sports equipment.

Images