Room temperature efficient self-healing waterborne polyurethane elastomer, preparation method and application thereof
By introducing a diketone structure and europium(III) lanthanide metal ions into an aqueous polyurethane elastomer for coordination crosslinking, a dynamic reversible network is constructed, which solves the problem of high-temperature repair in existing thermally responsive self-healing materials and achieves efficient self-healing and reprocessable properties at room temperature.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2025-01-22
- Publication Date
- 2026-05-12
AI Technical Summary
Existing thermally responsive self-healing materials require high temperatures for repair and have long repair times, making it difficult to achieve efficient repair at room temperature.
By introducing maleic dihydrazide molecules with a diketone structure and europium(III) lanthanide metal ions into waterborne polyurethane elastomers for coordination crosslinking, a dynamically reversible non-covalent crosslinking network is constructed, enabling room temperature self-healing.
Waterborne polyurethane elastomers achieve efficient self-healing at room temperature, with short repair time, a fracture repair efficiency of up to 98.5%, and are reprocessable and shape memory functionalities.
Smart Images
Figure CN119899352B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a room-temperature high-efficiency self-healing waterborne polyurethane elastomer, its preparation method, and its application. Background Technology
[0002] The development of novel functional materials is often inspired by novel ideas found in nature, and materials science has made significant achievements in the field of biomimetic materials. For example, inspired by the lotus leaf's ability to emerge from mud unsullied and not stick to water, researchers have prepared antifouling and hydrophobic materials and coatings; inspired by geckos' ability to climb walls, humans have created biomimetic gecko-adhesive materials. The self-healing ability of polymers is also inspired by organisms in nature, and it has attracted widespread attention since its introduction.
[0003] There are various methods for preparing self-healing materials, with the use of dynamic and reversible covalent and non-covalent interactions being two of the mainstream approaches currently being researched. In intermolecular interactions in supramolecular chemistry, as a typical form of dynamic and reversible non-covalent interaction, are an effective strategy for endowing polymer materials with 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 reported intrinsically self-healing polymer materials require external energy or material stimulation to trigger the repair process, such as heat, light, initiators, or solvents. Photoresponsive self-healing materials are typically produced by introducing photoinitiating groups into the polymer; these materials only need to expose the damaged material to light to complete the repair process. While their advantages are significant, their disadvantages are also apparent. For materials with poor transparency and large thickness, this approach is not ideal. In contrast, thermally responsive self-healing strategies have strong material universality, unaffected by material morphology and size. More importantly, this strategy can achieve highly efficient repair results with high reliability. Thermally responsive self-healing is currently the most studied type of repair. However, most reported thermally responsive self-healing materials generally require high repair temperatures and long repair times.
[0005] Therefore, there is an urgent need to provide a new self-healing material that requires a low thermal excitation temperature, has a short repair time, and high repair efficiency for self-healing. Summary of the Invention
[0006] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a room-temperature high-efficiency self-healing waterborne polyurethane elastomer, its preparation method, and its application. The waterborne polyurethane elastomer of this invention requires a low thermal excitation temperature for self-healing, can repair itself at room temperature, has a short repair time, and high repair efficiency.
[0007] The waterborne polyurethane elastomer provided by this invention achieves efficient self-healing at room temperature and also possesses low-temperature repair capabilities. Maleic dihydrazide (MDA) molecules rich in diketone structures are introduced into the molecular chain of a cationic waterborne polyurethane prepolymer with N-methyldiethanolamine (MEDA) as a hydrophilic group via stepwise polymerization, thereby modifying the prepolymer. Subsequently, the polyurethane prepolymer containing diketone ligand groups is further reacted with lanthanide metal ions europium(III) (Eu... 3+ Coordination crosslinking is performed to construct a dynamically reversible nonvalent crosslinked network between polymer chains. By controlling the amount of coordination crosslinking network introduced, tunable Eu polymers can be prepared. 3+ Ion-coordinate bond-toughened waterborne polyurethane elastomers. These elastomers exhibit typical elastomer behavior, with tensile strengths reaching up to 17.78 MPa and elongation at break reaching 2050%. Regulating the construction of the coordination crosslinking network endows waterborne polyurethane elastomers with efficient self-healing capabilities at room temperature and outstanding low-temperature repair properties, and also grants them reprocessability and shape memory functions.
[0008] The first aspect of the present invention provides a room-temperature efficient self-healing waterborne polyurethane elastomer.
[0009] Specifically, a room-temperature efficient self-healing waterborne polyurethane elastomer comprises a cationic waterborne polyurethane prepolymer molecular chain with diketone ligand groups.
[0010] Preferably, the waterborne polyurethane elastomer further includes Eu. 3+ .
[0011] Preferably, the diketone ligand group is provided by maleic dihydrazide.
[0012] Preferably, the hydrophilic groups in the cationic waterborne polyurethane prepolymer molecular chain 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] A 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 high-efficiency self-healing waterborne polyurethane elastomer includes the following steps:
[0017] (1) Mix isocyanate, polyether alcohol, N-methyldiethanolamine and organic solvent, add catalyst, and carry out the first reaction under a protective gas atmosphere to obtain substance a. Then add substance containing diketone ligand group to carry out the second reaction. Then add acid to carry out the third reaction to obtain waterborne polyurethane elastomer prepolymer.
[0018] (2) Add ice water to the waterborne polyurethane elastomer prepolymer, emulsify to obtain waterborne polyurethane elastomer emulsion, and cure to obtain the waterborne polyurethane elastomer.
[0019] Preferably, after the third reaction is completed, an organic compound containing europium is added to carry out a fourth reaction.
[0020] Preferably, the molar ratio of isocyanate, polyether alcohol, and N-methyldiethanolamine is 25.54-30.14:10:(11-15), and more preferably 25.54-30.14:10:13.16.
[0021] Preferably, the 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 polytetrahydrofuran ether diol (PTMG).
[0024] Preferably, the organic solvent includes acetone.
[0025] Preferably, the 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 organotin 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℃ and the reaction time is 1-3 hours. More preferably, the temperature of the first reaction is 62-65℃ and the reaction time is 2-3 hours.
[0029] Preferably, the ratio of the polyether alcohol to the substance containing the 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 the diketone ligand group includes maleic dihydrazide (MDA).
[0031] Preferably, the temperature of the second reaction is 55-60°C and the reaction time is 4-6 hours. More preferably, the temperature of the second reaction is 58-60°C and the reaction time is 5-6 hours.
[0032] Preferably, the ratio of polyether alcohol to acid is 10 mmol:(11-15) mmol, more preferably 10 mmol:(12-13.66) mmol.
[0033] Preferably, the acid includes glacial acetic acid.
[0034] Preferably, the temperature of the third reaction is 15-35℃ and the reaction time is 0.1-0.5 hours. More preferably, the temperature of the third reaction is 25-35℃ and the reaction time is 0.2-0.5 hours.
[0035] Preferably, the ratio of the amount of polyether alcohol to the organic matter of europium is 10 mmol:(0.5-2.5) mmol, and more preferably 10 mmol:(0.79-2.32) mmol.
[0036] Preferably, the organic form of europium includes europium trifluoromethanesulfonate (Eu(CF3SO3)3).
[0037] Preferably, the temperature of the fourth reaction is 35-43°C and the reaction time is 12-24 hours. More preferably, the temperature of the fourth reaction is 40-43°C and the reaction time 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 includes the following steps:
[0041] (1) Polytetrahydrofuran ether diol (PTMG) and N-methyldiethanolamine (MEDA) are used after being vacuum dried at 100-110℃ for 3 hours;
[0042] (2) Dissolve hexamethylene diisocyanate (HDI), PTMG and MEDA in 40-50 mL of acetone, place them in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer, add dibutyltin dilaurate (DBTDL) catalyst, and react at 60-65 °C for 2-3 h under a nitrogen atmosphere.
[0043] (3) Cool the reaction temperature of step (2) to below 55°C, add maleic dihydrazide (MDA), and continue the reaction at 55-60°C for 4-6 hours;
[0044] (4) Reduce the temperature of the system after the reaction in step (3) to below 35°C, neutralize the tertiary amine groups of the MEDA unit on the prepolymer chain with a slight excess of glacial acetic acid (AcOH), react for 20-30 min, and then slowly add the acetone solution of europium trifluoromethanesulfonate (Eu(CF3SO3)3) dropwise to the above prepolymer solution, and react at 42-43°C for 20-24 h to obtain the acetone solution of the 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 needs to be added to adjust its viscosity so that the reverse emulsification can be carried out in the next step. Finally, ice-cold deionized water is added to the system at a constant rate, and high-speed shear dispersion emulsification is carried out at the same time. The resulting mixture is left to stand at room temperature overnight.
[0046] (6) The system obtained in step (5) is subjected to vacuum evaporation at a temperature not higher than 40°C to remove excess acetone from the system, resulting in a uniform and stable aqueous polyurethane elastomer emulsion. The emulsion is then cured to obtain the aqueous polyurethane elastomer.
[0047] A third aspect of the present invention provides an application of a room-temperature efficient self-healing waterborne polyurethane elastomer.
[0048] The above-mentioned waterborne polyurethane elastomers are used in the fields of automobiles, construction, aerospace, instruments and equipment, or sports equipment.
[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0050] This invention utilizes MDA containing diketone coordination units to functionalize and chemically modify cationic waterborne polyurethane molecular chains, and introduces free lanthanide coordination metal ions (Eu) into the system. 3+ Electron-rich diketone structures can be converted into electron-deficient Eu groups under the influence of charge. 3+ Ion capture spontaneously forms a strong coordination bond, an Eu3+ Ions can capture three diketone structural units, thereby forming an effective dynamic reversible cross-linked network structure between polymer molecular chains. By adjusting the amount of ligands and coordinating metals introduced, the balance between intermolecular forces and chain mobility can be controlled, thus preparing waterborne polyurethane elastomers with excellent mechanical properties, flexibility, thermal stability, and dynamic viscoelastic behavior. The tensile strength of the waterborne polyurethane elastomer can exceed 6 MPa, and the elongation at break can exceed 2000%. The construction of a robust dynamic reversible cross-linked network endows the waterborne polyurethane elastomer with efficient biomimetic self-healing ability at room temperature and outstanding low-temperature repair performance, while also giving it reprocessability and shape memory functions. The waterborne polyurethane elastomer damaged by fracture can achieve a fracture self-healing efficiency of 98.5% after 24 hours of repair at room temperature, and its strength after repair is still as high as 6.06 MPa, and its elongation at break is as high as 2105.56%. It is worth noting that it can still exhibit fracture repair efficiencies of up to 76.94% and 51.07% at 0℃ and -30℃, respectively. Furthermore, the repaired waterborne polyurethane elastomer can withstand multiple cycles of stretching, exhibiting good elastic behavior. Attached Figure Description
[0051] Figure 1 This is a flowchart illustrating the synthesis of the WPU-MEu1 aqueous emulsion in Example 1 of the present invention.
[0052] Figure 2 The infrared spectrum of the prepared waterborne polyurethane elastomer is shown in the example.
[0053] Figure 3 The following is a partial infrared spectrum of the prepared waterborne polyurethane elastomer as an example.
[0054] Figure 4 The diagram shows the self-healing properties of the waterborne polyurethane elastomers prepared in the examples and comparative examples.
[0055] Figure 5 This image shows the WPU-MEu1 after room temperature restoration, demonstrating its load-bearing capacity of 2kg and its shape memory function. Detailed Implementation
[0056] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.
[0057] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.
[0058] Example 1
[0059] A method for preparing a room-temperature efficient self-healing waterborne polyurethane elastomer includes the following steps:
[0060] First, 25.54 mmol HDI (hexamethylene diisocyanate), 10 mmol PTMG (polytetrahydrofuran ether diol), and 13.16 mmol MEDA (N-methyldiethanolamine) were dissolved in 50 mL acetone and placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (approximately 0.04 g) were added, and the mixture was reacted at 65 °C for 3 h under a nitrogen atmosphere. The resulting mixture was then cooled to below 55 °C, and 2.38 mmol MDA (maleic acid dihydrazide) was added. The reaction was continued at 60 °C for 6 h. Subsequently, the system temperature was lowered to below 35 °C, and the tertiary amine groups of the MEDA units on the prepolymer chain were neutralized with a slight excess of 13.66 mmol AcOH. The reaction was carried out for 30 min to obtain a prepolymer solution. Then, 0.79 mmol An 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 waterborne polyurethane elastomer prepolymer. After the reaction was completed, the system temperature was lowered to room temperature. Finally, ice-cold deionized water was added to the acetone solution of waterborne polyurethane elastomer prepolymer at a uniform rate, while high-speed shear dispersion was carried out for emulsification. The resulting mixture was left to stand at room temperature overnight. Excess acetone in the system was removed by vacuum evaporation at a temperature not exceeding 40°C to obtain a homogeneous and stable waterborne emulsion of WPU-MEu1. The waterborne emulsion of WPU-MEu1 was poured into a silicone mold and left to stand on a horizontal platform at room temperature to evaporate moisture and cure for 12 hours. Then it was placed in a forced-air oven and dried at 60°C for 48 hours to obtain the waterborne polyurethane elastomer (denoted as WPU-MEu1).
[0061] Example 2
[0062] A method for preparing a room-temperature efficient self-healing waterborne polyurethane elastomer includes the following steps:
[0063] First, 27.78 mmol HDI (hexamethylene diisocyanate), 10 mmol PTMG (polytetrahydrofuran ether diol), and 13.16 mmol MEDA (N-methyldiethanolamine) were dissolved in 50 mL acetone and placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (approximately 0.04 g) were added, and the mixture was reacted at 65 °C for 3 h under a nitrogen atmosphere. The resulting mixture was then cooled to below 55 °C, and 4.62 mmol MDA (maleic acid dihydrazide) was added. The reaction was continued at 60 °C for 6 h. Subsequently, the system temperature was lowered to below 35 °C, and a slight excess of 13.66 mmol AcOH was used to neutralize the tertiary amine groups of the MEDA units on the prepolymer chain. The reaction was carried out for 30 min to obtain a prepolymer solution. Then, 1.54 mmol An 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 waterborne polyurethane elastomer prepolymer. After the reaction was completed, the system temperature was lowered to room temperature. Finally, ice-cold deionized water was added to the acetone solution of waterborne polyurethane elastomer prepolymer at a uniform rate, while high-speed shear dispersion was carried out for emulsification. The resulting mixture was left to stand at room temperature overnight. Excess acetone in the system was removed by vacuum evaporation at a temperature not exceeding 40°C to obtain a homogeneous and stable WPU-MEu2 waterborne emulsion. The WPU-MEu2 waterborne emulsion was poured into a silicone mold and left to stand on a horizontal platform at room temperature to evaporate moisture and cure for 12 hours. Then, it was placed in a forced-air oven and dried at 60°C for 48 hours to obtain the waterborne polyurethane elastomer (denoted as WPU-MEu2).
[0064] Example 3
[0065] A method for preparing a room-temperature efficient self-healing waterborne polyurethane elastomer includes the following steps:
[0066] First, 30.14 mmol HDI (hexamethylene diisocyanate), 10 mmol PTMG (polytetrahydrofuran ether diol), and 13.16 mmol MEDA (N-methyldiethanolamine) were dissolved in 50 mL acetone and placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (approximately 0.04 g) were added, and the mixture was reacted at 65 °C for 3 h under a nitrogen atmosphere. The resulting mixture was then cooled to below 55 °C, and 6.98 mmol MDA (maleic acid dihydrazide) was added. The reaction was continued at 60 °C for 6 h. Subsequently, the system temperature was lowered to below 35 °C, and the tertiary amine groups of the MEDA units on the prepolymer chain were neutralized with a slight excess of 13.66 mmol AcOH. The reaction was carried out for 30 min to obtain a prepolymer solution. Then, 2.32 mmol An 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 waterborne polyurethane elastomer prepolymer. After the reaction was completed, the system temperature was lowered to room temperature. Finally, ice-cold deionized water was added to the acetone solution of waterborne polyurethane elastomer prepolymer at a uniform rate, while high-speed shear dispersion was carried out for emulsification. The resulting mixture was left to stand at room temperature overnight. Excess acetone in the system was removed by vacuum evaporation at a temperature not exceeding 40°C to obtain a homogeneous and stable WPU-MEu3 waterborne emulsion. The WPU-MEu3 waterborne emulsion was poured into a silicone mold and left to stand on a horizontal platform at room temperature to evaporate moisture and cure for 12 hours. Then, it was placed in a forced-air oven and dried at 60°C for 48 hours to obtain the waterborne polyurethane elastomer (denoted as WPU-MEu3).
[0067] Example 4
[0068] A method for preparing an aqueous polyurethane elastomer includes the following steps:
[0069] First, 25.54 mmol HDI (hexamethylene diisocyanate), 10 mmol PTMG (polytetrahydrofuran ether glycol), and 13.16 mmol MEDA (N-methyldiethanolamine) were dissolved in 50 mL of acetone and placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (approximately 0.04 g) were added, and the mixture was reacted at 65 °C for 3 h under a nitrogen atmosphere. The resulting mixture was then cooled to below 55 °C, and 2.38 mmol MDA (maleic acid dihydrazide) was added. The reaction was continued at 60 °C for 6 h. Subsequently, the system temperature was lowered to below 35 °C, and a slight excess of 13.66 mmol of [a specific chemical compound] was added. AcOH neutralizes the tertiary amine groups of the MEDA units on the prepolymer chain and reacts for 30 min to obtain a prepolymer solution. The system temperature is then lowered to room temperature. Finally, ice-cold deionized water is added to the prepolymer solution at a uniform rate while simultaneously performing high-speed shear dispersion for emulsification. The resulting mixture is left to stand at room temperature overnight. Excess acetone in the system is removed by vacuum evaporation at a temperature not exceeding 40°C to obtain a homogeneous and stable WPU-M aqueous emulsion. The WPU-M aqueous emulsion is poured into a silicone mold and left to stand on a horizontal platform at room temperature to evaporate moisture and cure for 12 h. Then, it is placed in a forced-air oven and dried at 60°C for 48 h to obtain an aqueous polyurethane elastomer (denoted as WPU-M).
[0070] Comparative Example 1
[0071] A method for preparing an aqueous polyurethane elastomer includes the following steps:
[0072] First, 25.54 mmol HDI (hexamethylene diisocyanate), 10 mmol PTMG (polytetrahydrofuran ether diol), and 13.16 mmol MEDA (N-methyldiethanolamine) were dissolved in 50 mL acetone and placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (approximately 0.04 g) were added, and the mixture was reacted at 65 °C for 3 h under a nitrogen atmosphere. Subsequently, the system temperature was lowered to below 35 °C, and the tertiary amine groups of the MEDA units on the prepolymer chain were neutralized with a slight excess of 13.66 mmol AcOH. The reaction was carried out for 30 min to obtain a prepolymer solution. Then, 0.79 mmol... An 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 a prepolymer acetone solution. After the reaction was completed, the system temperature was lowered to room temperature. Finally, ice-cold deionized water was added to the prepolymer acetone solution at a uniform rate, and high-speed shear dispersion was carried out for emulsification. The resulting mixture was left to stand at room temperature overnight. Excess acetone in the system was removed by vacuum evaporation at a temperature not exceeding 40°C to obtain a homogeneous and stable WPU+Eu aqueous emulsion. The WPU+Eu aqueous emulsion was poured into a silicone mold and left to stand on a horizontal platform at room temperature to evaporate moisture and cure for 12 hours. Then, it was placed in a forced-air oven and dried at 60°C for 48 hours to obtain an aqueous polyurethane elastomer (denoted as WPU+Eu).
[0073] Comparative Example 2
[0074] A method for preparing an aqueous polyurethane elastomer includes the following steps:
[0075] First, 25.54 mmol HDI (hexamethylene diisocyanate), 10 mmol PTMG (polytetrahydrofuran ether diol), and 13.16 mmol MEDA (N-methyldiethanolamine) were dissolved in 50 mL of acetone and placed in a 500 mL four-necked round-bottom flask equipped with a mechanical stirrer. Two drops of DBTDL (dibutyltin dilaurate) catalyst (approximately 0.04 g) were added, and the reaction was carried out at 65 °C for 3 h under a nitrogen atmosphere. The system temperature was then lowered to below 35 °C, and a slight excess of 13.66 mmol of [a specific catalyst] was added. AcOH neutralizes the tertiary amine groups of the MEDA units on the prepolymer chain and reacts for 30 minutes. After the reaction, the system temperature is lowered to room temperature, and ice-cold deionized water is added at a uniform rate while high-speed shear dispersion is performed for emulsification. The resulting mixture is left to stand at room temperature overnight. Excess acetone in the system is removed by vacuum evaporation at a temperature not exceeding 40°C to obtain a homogeneous and stable WPU aqueous emulsion. The WPU aqueous emulsion is poured into a silicone mold and left to stand on a horizontal platform at room temperature to evaporate moisture and cure for 12 hours. Then, it is placed in a forced-air oven and dried at 60°C for 48 hours to obtain an aqueous polyurethane elastomer (denoted as WPU).
[0076] Product effectiveness test
[0077] Figure 1 This is a flowchart illustrating the synthesis process of the WPU-MEu1 aqueous emulsion in Example 1 of the present invention. Figure 2 The infrared spectrum of the prepared waterborne polyurethane elastomer is shown in the example. Figure 3 The image shows a partial infrared spectrum of the aqueous polyurethane elastomer prepared as an example. Figure 2 and Figure 3 In this context, "Wavenumber" and "Transmittance" both refer to the wavenumber. The functional groups of the samples were measured using a TENSOR27 Fourier transform infrared spectrometer (Bruker, Germany) in ATR mode (total reflectance attenuation mode), with a scanning range of 4000–500 cm⁻¹. -1 .
[0078] The waterborne polyurethane elastomers (in thin film form) prepared in the above examples and comparative examples were tested for self-healing properties, and the results are as follows: Figure 4 As shown.
[0079] Self-healing performance is primarily assessed by evaluating the degree to which the mechanical strength of the sample recovers within a set timeframe. First, the sample membrane is cut into two segments and then reassembled. Subsequently, the sample is allowed to self-heal under different time and temperature conditions, and the degree of recovery of its mechanical properties is then 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, as follows: η=σ / σ0*100%.
[0081] Figure 4 The diagram shows the self-healing properties of the waterborne polyurethane elastomers prepared in the examples and comparative examples. Figure 4 The stress-strain curves (corresponding to Figures (a), (b), (c), and (g)) and self-healing efficiencies (corresponding to Figures (d), (e), (f), and (j)) of WPU, WPU-M, WPU-MEu2, and WPU-MEu3 after self-healing for a certain period of time at room temperature, 0℃, and -30℃ are shown in Figures (h) and (k), respectively). The stress-strain curves (corresponding to Figure (i)) and self-healing efficiencies (corresponding to Figure (l)) of WPU-MEu1 after self-healing for different durations at room temperature are shown in Figure (h) and (k), respectively. The stress-strain curves (corresponding to Figure (i)) of WPU-MEu1 after 4 days of repair at 0℃ and -30℃ are also shown in Figure (l). The cyclic stress-strain curve of WPU-MEu1 after 48 hours of self-healing at room temperature is also shown in Figure (l). Figure 4In this context, "original" refers to the original waterborne polyurethane elastomer, "D" represents day, "Stress" represents stress, "Strain" represents strain, "Healing Efficiency" represents self-healing efficiency, and "1st cycle," "2nd cycle," "3rd cycle," "4th cycle," "5th cycle," "6th cycle," "7th cycle," "8th cycle," "9th cycle," and "10th cycle" represent the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, and 10th cycles, respectively. Figure 4 It can be seen that the waterborne polyurethane elastomer prepared in the embodiments of the present invention has good room temperature repair effect, especially high strength after self-repair.
[0082] Figure 5 This image shows the WPU-MEu1 after room temperature restoration, demonstrating its load-bearing capacity of 2kg and its shape memory function. Figure 5 (“cut” means to shorten) Image (a) shows the result of displaying a 2kg load, and Image (b) shows the result of demonstrating the shape memory function.
[0083] Figure 5 The results of a load demonstration on a WPU-MEu1 specimen repaired at room temperature are shown. The dumbbell-shaped WPU-MEu1 specimen, 35mm long, has a narrow section 2mm wide and 0.62mm thick. After being folded in half, two 1000g weights were hung at the break. The specimen effectively lifted a 2000g weight, demonstrating that WPU-MEu1 possesses excellent self-healing ability and mechanical properties. Figure 5 (a)). Furthermore, the stretched spline that has undergone yielding deformation can rapidly recover its initial shape and dimensions under a 50°C thermal environment. Figure 5 (b) indicates that the prepared waterborne polyurethane elastomer also has shape memory function.
Claims
1. A method for preparing a waterborne polyurethane elastomer, characterized in that, The preparation method includes the following steps: (1) Isocyanate, polyether alcohol, N-methyldiethanolamine and organic solvent are mixed, a catalyst is added, and a first reaction is carried out under a protective gas atmosphere to obtain substance a. Then a substance containing diketone ligand groups is added and a second reaction is carried out. Then an acid is added and a third reaction is carried out. Then an organic compound containing europium is added and a fourth reaction is carried out to obtain an aqueous polyurethane elastomer prepolymer. The substance containing diketone ligand groups is maleic dihydrazide. The aqueous polyurethane elastomer prepolymer is a cationic aqueous polyurethane prepolymer containing diketone ligand groups. (2) Add ice water to the waterborne polyurethane elastomer prepolymer, emulsify to obtain waterborne polyurethane elastomer emulsion, and cure to obtain the waterborne polyurethane elastomer.
2. The preparation method according to claim 1, 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%.
3. The preparation method according to claim 1, characterized in that, The molar ratio of the isocyanate, polyether alcohol, and N-methyldiethanolamine is 25.54-30.14:10:(11-15); and / or the ratio of the polyether alcohol to the organic solvent is 10 mmol:(40-60) mL.
4. The preparation method according to claim 1, characterized in that, The polyether alcohol includes polytetrahydrofuran ether diol; and / or, the ratio of the catalyst to the polyether alcohol is 0.02-0.05 g: 10 mmol; and / or, the catalyst includes an organotin catalyst.
5. The preparation method according to claim 1, characterized in that, The temperature of the first reaction is 60-65°C, and the reaction time is 1-3 hours; and / or, the ratio of the polyether alcohol to the substance containing the diketone ligand group is 10 mmol: (2.0-7.5) mmol.
6. The preparation method according to claim 3, characterized in that, The second reaction is carried out at a temperature of 55-60°C for 4-6 hours; and / or, the ratio of the polyether alcohol to the acid is 10 mmol:(11-15) mmol; and / or, the acid includes glacial acetic acid; and / or, the third reaction is carried out at a temperature of 15-35°C for 0.1-0.5 hours; and / or, the ratio of the polyether alcohol to the organic europium is 10 mmol:(0.5-2.5) mmol; and / or, the organic europium includes europium trifluoromethanesulfonate; and / or, the fourth reaction is carried out at a temperature of 35-43°C for 12-24 hours.
7. The application of the waterborne polyurethane elastomer prepared by the preparation method according to any one of claims 1-6 in the fields of automobiles, construction, aerospace, instruments and equipment or sports equipment.