High-toughness self-repairing polyurethane based on ureido / disulfide bond dual dynamic network and preparation method thereof

Abstract

The invention discloses high-toughness self-repairing polyurethane based on a ureido / disulfide bond dual dynamic network and a preparation method of the high-toughness self-repairing polyurethane, and belongs to the technical field of self-repairing high polymer materials. The structural formula of the thermal stimulation repairing polyurethane is shown in the specification. The polyurethane is formed by mixing and polycondensing polyether amine, diaminodiphenyl disulfide and dicyclohexylmethane diisocyanate. According to the invention, polyether amine is used as a raw material, green synthesis without a catalyst is realized, ureido generated by the reaction forms a hydrogen bond network with extremely strong dynamic property and cooperates with a disulfide bond, a repair process is completed at 50 DEG C, the toughness can reach 40.55 MJ / m < 3 >, the fast recovery capability is realized, the material can be stretched to be 20 times of the original length, and the service life of the material is prolonged. Good network dynamic property is achieved at the room temperature, and high self-repairing efficiency is achieved at the room temperature.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of self-repairing materials, and relates to a high-toughness self-repairing polyurethane based on a urea group / dithio bond double dynamic network and a preparation method thereof. BACKGROUND

[0002] The dynamically responsive heat-stimulating self-repairing polyurethane is widely applied to industrial production, such as elastomers, plastics, fibers, adhesives, coatings, food, medical treatment and the like, due to its high strength, high toughness, fatigue resistance, higher stability and simple and environment-friendly processing process. The thermoplastic polyurethane material is widely applied to various scenes, which is due to the adjustability of the strength and toughness. At present, a common method in the industry is to blend different types of polyurethane materials to change the hardness and ductility, for example, polyether polyurethane and polyester polyurethane are blended to prepare polyurethane which has the water resistance and flexibility of polyether polyurethane and the wear resistance, tear resistance and high tensile strength of polyester polyurethane. However, the blending method has obvious disadvantages. When the hard segment ratio in the blending system is high, the compatibility of the two types of polyurethane is poor. In order to better adjust the hardness and ductility of the polyurethane, the structure design strategy of the micro-phase separation structure with soft and hard units alternately is widely applied to the configuration design of the strong and tough thermoplastic polyurethane. The polyurethane material is prone to produce micro-cracks during the processing and cooling process or under strong impact, and the damage part will gradually expand during long-term use. If the damage cannot be repaired in time, the performance will be rapidly reduced and damaged, which easily causes use failure or other serious consequences.

[0003] Biological systems in nature have excellent self-healing ability, which can realize autonomous repair through complex physiological mechanisms after damage. Inspired by this, material scientists have devoted to developing self-healing polymer materials. Among them, polyurethane materials based on dynamic disulfide bonds have become a research hotspot due to their unique stimulus-responsive characteristics. In 2022, Professor Chen Tao's team at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, prepared a self-healing elastomer with a tensile strength of 35 MPa by precisely controlling the distribution of disulfide bonds in the hard segment. Its repair efficiency reached more than 95% after 24 hours of repair at 70 ℃, showing the high-efficiency dynamic exchange ability of disulfide bonds under thermal stimulation. This design strategy of precisely introducing disulfide bonds into the hard segment area provides a new idea for balancing the mechanical properties and self-healing efficiency of materials. In 2023, Professor Gao Chao's group at Zhejiang University successfully prepared a transparent polyurethane film with room-temperature self-healing function by introducing a diphenyl disulfide structural unit into the polyurethane main chain and using microphase separation structure regulation. The material has a visible light transmittance of more than 90% and an elongation at break of up to 800%, and can realize autonomous repair of damaged parts at 25 ℃, which is attributed to the dynamic disproportionation reaction of disulfide bonds at room temperature. Notably, the material can maintain more than 85% of its original mechanical properties after 5 cycles of damage-repair, showing good recyclable repair ability. In 2024, Professor Li Yuesheng's team at Tianjin University prepared a polyurethane elastomer with a double dynamic network structure by using a disulfide bond-containing diol compound as a chain extender and reacting with isophorone diisocyanate. The material exhibits excellent comprehensive performance: a tensile strength of 42 MPa, an elongation at break of more than 600%, and a repair efficiency of 92% after 12 hours of repair at 50 ℃. The synergistic design of double dynamic bonds not only ensures the high mechanical strength of the material, but also endows it with high-efficiency self-healing ability.

[0004] However, the above-mentioned material systems still have obvious limitations. The material developed by Ningbo Institute of Materials Technology and Engineering requires a high repair temperature (70 ℃), limiting its application in heat-sensitive environments; the room-temperature self-healing material reported by Zhejiang University has a relatively low mechanical strength (tensile strength < 15 MPa), making it difficult to meet the needs of high-load application scenarios; the double dynamic network material studied by Tianjin University has a good balance between mechanical properties and repair efficiency, but the synthesis process is complex and the raw material cost is high, which is not conducive to large-scale preparation. These limitations prompt us to seek new molecular design strategies to develop new self-healing polyurethane materials with mild repair conditions, excellent mechanical properties, and simple preparation.

[0005] In recent years, intrinsic self-healing materials based on reversible non-covalent and reversible covalent interactions in polymers have gradually become a research hotspot in the field of self-healing materials due to their theoretical ability to achieve an unlimited number of self-healing processes, thus becoming a new generation of self-healing material systems. Existing reversible covalent bonds used to construct intrinsic self-healing materials mainly include disulfide bond reactions, Diels-Alder reactions, and dynamic covalent bonds in borate esters. Reversible non-dynamic covalent bonds mainly include hydrogen bonds and ionic polymers. For example, Chinese patent CN202310197031.X discloses a method for preparing a dual dynamic self-healing polyurethane elastomer. This method uses polyether glycol as the soft segment, reacts it with diisocyanate to prepare a prepolymer, and then performs chain extension with a separately synthesized diol containing disulfide bonds. While this technical approach can produce self-healing polyurethanes, the reaction rate between the hydroxyl groups and isocyanate groups in polyether glycols is relatively slow, usually requiring the addition of catalysts such as organotin to ensure the smooth progress of the reaction. The hydrogen bonds formed by the urethane groups generated from the reaction of alcohol hydroxyl groups and isocyanates lack dynamism at lower temperatures, which to some extent limits the migration and rearrangement of polymer chain segments, hindering efficient self-healing.

[0006] Furthermore, the aforementioned reversible dynamic covalent bonds all require external stimuli (such as light, heat, and solvents) to achieve the breaking, recombination, or exchange process. Therefore, self-healing materials based on reversible covalent bonds are difficult to achieve room temperature self-healing. There is often a balance between their mechanical properties (modulus and toughness) and dynamic self-healing performance, making it difficult to simultaneously achieve both mechanical properties and self-healing effects, which greatly limits the practical application and promotion of such materials.

[0007] Therefore, developing a novel polyurethane elastomer that has a simple synthesis process, does not rely on catalysts, can achieve efficient self-healing under milder conditions (even at room temperature), and also has ultra-high toughness is of profound significance for promoting the application of self-healing elastomers. Summary of the Invention

[0008] The purpose of this invention is to provide a high-toughness self-healing polyurethane based on a urea / disulfide bond dual dynamic network and its preparation method.

[0009] The technical solution for achieving the objective of this invention is as follows: The present invention relates to a high-toughness self-healing polyurethane based on a urea / disulfide bond dual dynamic network and its preparation method, the structural formula of which is as follows: ; Where 10≤n≤60.

[0010] The present invention relates to a high-toughness self-healing polyurethane based on a dual dynamic network of urea groups and disulfides, which is prepared from diaminodiphenyl disulfide, polyetheramine (PPGBA), dicyclohexylmethane diisocyanate, and a small molecule monohydric alcohol. The structural formula of the polyetheramine is as follows: , 10≤n≤60.

[0011] The present invention relates to a high-toughness self-healing polyurethane based on a urea / disulfide bond dual dynamic network and its preparation method, the specific steps of which are as follows: (1) Under an inert gas atmosphere, polyetheramine and diaminodiphenyl disulfide were dissolved in N,N'-dimethylformamide solvent to prepare mixed solution I; (2) Dissolve dicyclohexylmethane diisocyanate in N,N'-dimethylformamide solvent to prepare mixed solution II. Then add mixed solution II dropwise to mixed solution I at 0~4 °C and stir for 8~12 h to obtain initial product solution III. The molar ratio of the sum of the molar amounts of dicyclohexylmethane diisocyanate, polyetheramine and diaminodiphenyl disulfide is 100:90~100. (3) Heat the initial product solution III at 70-85 °C for 6-12 h to obtain the initial product solution IV; (4) Add the small molecule monohydric alcohol to the initial product solution IV and stir to mix evenly to obtain polymer solution V.

[0012] (5) The polymer solution was dried to remove the solvent, and disulfide bond dynamic response thermal stimulation self-healing polyurethane was obtained.

[0013] Furthermore, the molar ratio between polyetheramine and diaminodiphenyl disulfide is 3:7 to 7:3; Preferably, in step (1), the molecular weight of the polyetheramine is 2000.

[0014] Preferably, in step (2), the dropping rate is 800~1000 μL / min.

[0015] Preferably, in step (2), the concentration of dicyclohexylmethane diisocyanate in the mixed solution II is 0.32~0.48 mmol / mL.

[0016] Preferably, in step (4), the small molecule monohydric alcohol is selected from methanol, ethanol, butanol, n-butanol or propanol, and the purpose of adding the small molecule monohydric alcohol is to quench unreacted isocyanate.

[0017] Preferably, in step (4), the stirring time is 10 to 20 minutes.

[0018] Preferably, in step (4), the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to dicyclohexylmethane diisocyanate and small molecule monohydric alcohol is 100:98~100:50~300.

[0019] Preferably, in step (5), the drying process is to first dry at 80~90 ℃ for 24~36 h, and then place it under vacuum at 85~90 ℃ for 12~24 h.

[0020] The self-healing method of the high-toughness self-healing polyurethane based on the urea / disulfide bond dual dynamic network of the present invention specifically involves adding a solvent that stimulates repair to the high-toughness self-healing polyurethane based on the urea / disulfide bond dual dynamic network or placing the high-toughness self-healing polyurethane based on the urea / disulfide bond dual dynamic network at a temperature above 50 °C.

[0021] Preferably, the solvent for stimulating repair is selected from N,N'-dimethylformamide, N-methylpyrrolidone, n-butanol, or ethanol.

[0022] Furthermore, this invention provides the application of the above-mentioned high-toughness self-healing polyurethane based on a dual dynamic network of urea groups / disulfide bonds in the preparation of photothermal materials and electronic device interfaces.

[0023] The high-toughness self-healing polyurethane based on a dual dynamic network of urea groups and disulfide bonds of this invention is constructed through supramolecular multilevel hydrogen bonds and disulfide bonds. The stacking of its soft / hard phase units provides the material with high mechanical strength and good ductility. Under certain forces, the soft and hard phases dissociate and recombine successively, dissipating energy and exhibiting high toughness. At temperatures of 50 °C and higher, the disulfide bond stacked phase dissociates and recombines, achieving repair.

[0024] Compared with the prior art, the present invention has the following advantages: (1) This invention uses polyetheramine as a flexible chain segment. The reactivity of amino (-NH2) and isocyanate group (-NCO) is much higher than that of hydroxyl, and the reaction can proceed rapidly without the addition of any catalyst. This not only simplifies the production process, but also avoids the potential problems caused by catalyst residue, making the preparation process more green and environmentally friendly.

[0025] This invention utilizes the reaction of polyetheramine and diisocyanate to form a large number of urea groups in the polymer backbone. Compared to the urethane groups formed by the reaction of polyether alcohol and isocyanate, the urea groups exhibit stronger hydrogen bond dynamics, facilitating self-healing and resulting in a higher degree of hydrogen bond cohesion. The dynamically thermally responsive, heat-stimulated repair polyurethane of this invention possesses room temperature / sub-high temperature self-healing capabilities, achieving over 90% toughness restoration and 100% ductility restoration at 50°C; after 10 days at room temperature, the material's toughness recovery rate reaches 95%.

[0026] (2) This invention selects long-chain polyetheramines with a specific molecular weight as the soft segment and optimizes the ratio of soft to hard segments to prepare a heat / solvent responsive repair polyurethane with a toughness value as high as 40.55 MJ / m. -3 The maximum tensile strength is above 1.6 MPa, and the maximum elongation is about 20 times; the mechanical properties are stable when exposed to air, and it has good resistance to water vapor adsorption. (3) The high-toughness self-healing polyurethane based on the urea / disulfide bond dual dynamic network of the present invention can be repeatedly remelted and hot-pressed. Compared with traditional thermosetting polyurethane materials, it can be repeatedly recycled and effectively extend the service life of the material. (4) The preparation method of the high-toughness self-healing polyurethane based on the urea / disulfide bond dual dynamic network of the present invention is simple to operate, has high yield, stable repeatability, and is easy to promote in the market. Attached Figure Description

[0027] Figure 1 A schematic diagram of the preparation process of the dynamic thermal response thermally stimulated repair polyurethane prepared in Example 1; Figure 2 An optical microscope image of the dynamically thermally responsive thermally stimulated repair polyurethane prepared in Example 1 under a high-temperature atmosphere. Figure 3 The stress-strain curves of the dynamically thermally responsive thermally stimulated repair polyurethane prepared in Example 3 at different repair times at high temperature; Figure 4 Stress-strain curves of dynamically thermally responsive, heat-stimulated repair polyurethane prepared in Example 3 at different repair times at room temperature; Figure 5 Stress-strain curves of dynamic thermal response thermally stimulated repair polyurethane prepared in Comparative Example 4 at different repair times at room temperature; Figure 6 Stress-strain curves of the dynamically thermally responsive thermally stimulated repair polyurethane prepared in Example 1 at different tensile rates at high temperature; Figure 7 The stress-strain curve of the dynamic thermal response thermally stimulated repair polyurethane tensile recovery prepared in Example 1; Figure 8 The nuclear magnetic resonance spectrum of the dynamically thermally responsive thermally stimulated repair polyurethane prepared in Example 1; Figure 9 The XRD pattern of the dynamically thermally responsive, thermally stimulated repair polyurethane prepared in Example 1; Figure 10 Raman spectrum of the dynamically thermally responsive thermally stimulated repair polyurethane prepared in Example 1; Figure 11Stress-strain curves of the materials prepared in Examples 1, 2, 3, 4, and 5; Figure 12 Examples of cyclic stretching curves at different stretching ratios in Example 1; Figure 13 The stress-strain curves of Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 at different reaction temperatures are shown. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings.

[0029] Example 1

[0030] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 3.812 g of polyetheramine (molecular weight 2000) and 0.473 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 70-85 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0031] Example 2

[0032] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 4.574 g of polyetheramine (molecular weight 2000) and 0.379 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 70-85℃ for 6-12 h to obtain the initial product solution IV. d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0033] Example 3

[0034] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 3.049 g of polyetheramine (molecular weight 2000) and 0.568 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 75 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0035] Example 4

[0036] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 5.336 g of polyetheramine (molecular weight 2000) and 0.284 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 75 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0037] Example 5

[0038] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 2.287 g of polyetheramine (molecular weight 2000) and 0.663 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 75 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0039] Comparative Example 1

[0040] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 3.049 g of polyetheramine (molecular weight 2000) and 0.568 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 80 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0041] Comparative Example 2

[0042] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 3.049 g of polyetheramine (molecular weight 2000) and 0.568 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 70 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0043] Comparative Example 3

[0044] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 3.049 g of polyetheramine (molecular weight 2000) and 0.568 g of diaminodiphenyl disulfide were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain the initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyetheramine and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 65 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0045] Comparative Example 4

[0046] The preparation method of high-toughness self-healing polyurethane based on urea / disulfide bond dual dynamic network is as follows: a. Under an inert gas atmosphere, 3.049 g of polyether glycol (molecular weight 2000), 0.568 g of diaminodiphenyl disulfide, and 0.02 g of dibutyltin dilaurate catalyst were dissolved in 20 mL of N,N'-dimethylformamide solvent to prepare mixed solution I; b. Dissolve 1.000 g of dicyclohexylmethane diisocyanate in 10 mL of N,N'-dimethylformamide solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I prepared in step a at 0-4 °C at a dropping rate of 1000 μL / min. Stir the reaction for 8-12 h to obtain initial product solution III, wherein the molar ratio of the sum of the molar amounts of polyether glycol and diaminodiphenyl disulfide to that of dicyclohexylmethane diisocyanate is 99:100. c. Heat the initial product solution III obtained in step b at 65 °C for 6-12 h to obtain the initial product solution IV; d. Add 0.200 g (6.25 mmol) of methanol to the initial product solution IV prepared in step c, stir for 10 minutes to obtain polymer solution V; e. The polymer solution V obtained in step d is dried at 90 °C for 48 h, and then dried under vacuum at 90 °C for 24 h to obtain disulfide bond dynamic thermal response thermal stimulation repair polyurethane.

[0047] Table 1

[0048] Table 2:

[0049] Figure 1 The diagram shows the preparation process of the dynamic thermal response thermal stimulation repair polyurethane prepared in Example 1. As can be seen from the diagram, the preparation method of the present invention is simple. Figure 2 The image shows the repaired dynamic thermal response thermal stimulation repair polyurethane prepared in Example 1 under an optical microscope at 50 °C. As can be seen from the image, the scratches were completely repaired within 1 h. Figure 3 The stress-strain curves of the dynamic thermal response thermally stimulated repair polyurethane prepared in Example 3 at different repair times at high temperature are shown. After repairing at 50 °C for 24 h, the tensile elongation is 2126%, the maximum tensile strength is about 1.6 MPa, and the toughness value is 93% repaired, indicating that it has good repair ability at high temperature. Figure 4The stress-strain curves of the dynamic thermal response thermally stimulated repair polyurethane prepared in Example 3 at different repair times at room temperature are shown. After 10 days of repair at room temperature, the tensile elongation is 2156%, the maximum tensile strength is about 1.56 MPa, and the toughness value is 95% repaired, indicating that it has good repair ability at room temperature. Figure 5 The stress-strain curves of the dynamic thermal response thermally stimulated repair polyurethane prepared for Comparative Example 4 at different repair times at room temperature are shown. After 10 days of repair at room temperature, the tensile elongation is 2668%, the maximum tensile strength is about 1.36 MPa, and the toughness value is 78% repaired, indicating that its repair ability at room temperature is low. Figure 6 The stress-strain curves of the dynamically thermally responsive thermally stimulated repaired polyurethane prepared in Example 1 at different stretching rates at room temperature are shown in the figure. As can be seen from the figure, the faster the stretching rate, the greater the tensile strength and the lower the tensile elongation. Figure 7 The stress-strain curve of the dynamic thermal response thermally stimulated repair polyurethane tensile recovery prepared in Example 1 shows that the material can still maintain excellent mechanical properties after multiple stretching. Figure 8 The NMR spectrum of the dynamically thermally responsive thermally stimulated repaired polyurethane prepared in Example 1 shows that a bulging peak appears near δ=7.05 ppm, indicating that the polymer chain segment has a -NH-C-NH- structure, proving that the amino group reacts with the isocyanate group. The peak positions in the spectrum correspond one-to-one with the hydrogen-containing groups in the structural formula, indicating that Example 1 was successfully synthesized. Figure 9 The XRD pattern of the dynamically thermally responsive thermally stimulated repair polyurethane prepared in Example 1 shows that the prepared material does not exhibit crystallization. Figure 10 The Raman spectrum of the dynamically thermally responsive, heat-stimulated repair polyurethane prepared in Example 1 is shown in the figure. As can be seen from the figure, at 476 cm⁻¹... -1 There are obvious Raman scattering peaks, corresponding to -SS- bonds; Figure 11 The stress-strain curves of the materials prepared for Examples 1, 2, 3, 4, and 5 are shown in the figure. Example 1 has the highest toughness value. Figure 12 Examples of cyclic stretching curves at different stretching ratios in Example 1; Figure 13 For comparison of the mechanical properties of materials prepared in Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3, such as... Figure 13As shown in Table 2, the reaction temperature affects the mechanical properties of the material. At a reaction temperature of 75 °C (Example 3), the material obtained the highest toughness value. Compared with other temperatures (65 °C, 70 °C, 80 °C), the sample prepared at 75 °C had the lowest Young's modulus but the highest elongation at break, indicating that the reaction temperature has a significant impact on the degree of crosslinking and the hard phase accumulation of the material.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-toughness self-healing polyurethane based on a urea / disulfide bond dual dynamic network, characterized in that, The structure is as follows: ，10≤n≤60。 2. The preparation method of the dynamically responsive thermally stimulated self-healing polyurethane according to claim 1, characterized in that, (1) Under an inert gas atmosphere, polyetheramine and diaminodiphenyl disulfide are dissolved in an organic solvent to prepare mixed solution I. The structural formula of the polyetheramine is as follows: ，10≤n≤60； (2) Dissolve dicyclohexylmethane diisocyanate in an organic solvent to prepare mixed solution II. Then, add mixed solution II dropwise to mixed solution I at 0-4 °C and stir to react, to obtain the initial product solution III. (3) Heat the initial product solution III to obtain the initial product solution IV; (4) Add the small molecule monohydric alcohol to the initial product solution IV and stir to mix evenly to obtain polymer solution V; (5) Dry the polymer solution V to remove the solvent and obtain the self-healing polyurethane.

3. The preparation method according to claim 2, characterized in that, In the reaction raw materials, the total molar ratio of the isocyanate groups provided by dicyclohexylmethane diisocyanate to the amine groups provided by polyetheramine and diaminodiphenyl disulfide is 100:90~100.

4. The preparation method according to claim 2, characterized in that, In step (1), the number average molecular weight of the polyetheramine is 600~4000 g / mol.

5. The preparation method according to claim 2, characterized in that, In step (2), the dropping rate is 800~1000 μL / min; in the mixed solution II, the concentration of dicyclohexylmethane diisocyanate is 0.32~0.48 mmol / mL.

6. The preparation method according to claim 2, characterized in that, In step (3), the temperature of the heat treatment is 70~85 ℃.

7. The preparation method according to claim 2, characterized in that, In step (4), the small molecule monohydric alcohol is selected from methanol, ethanol, butanol, n-butanol or propanol.

8. The preparation method according to claim 2, characterized in that, In step (4), the molar ratio of the sum of the molar amounts of dicyclohexylmethane diisocyanate, polyetheramine, and diaminodiphenyl disulfide, and the molar ratio of the small molecule monohydric alcohol is 100:98~100:50~300.

9. The self-healing method for disulfide bond dynamic response thermal stimulation self-healing polyurethane according to claim 1, characterized in that, Specifically, the polyurethane should be placed in a temperature environment above 50 ℃, or placed in a room temperature environment for 1-10 days for repair.

10. The application of the disulfide bond dynamic response thermally stimulated self-healing polyurethane according to claim 1 in the preparation of self-healing elastomers, coatings, adhesives, photothermal materials or flexible electronic devices.

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