Non-contact high-strength self-repairing polyurethane material and preparation method thereof

Abstract

The invention relates to a non-contact high-strength self-repairing polyurethane material and a preparation method thereof. The preparation method comprises the following steps: 1) weighing raw materials such as MXene, dicyclohexylmethane diisocyanate and polyether polyol; 2) preparing polyurethane with a self-repairing function; and 3) dispersing MXene in polyurethane, and curing to obtain the non-contact high-strength self-repairing polyurethane material. The prepared non-contact high-strength self-repairing polyurethane material is excellent in mechanical performance, good in self-repairing performance and photo-thermal performance, mild in reaction condition, simple in process, green, environmentally friendly and suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of self-repairing materials, and in particular to a non-contact high-strength self-repairing polyurethane material and a preparation method thereof. Background Art

[0002] Self-healing polymer materials have important application value in aerospace, flexible electronics, smart coatings and other fields. They can achieve autonomous repair after damage through dynamic chemical bonds (such as disulfide bonds, imine bonds) or physical effects (such as hydrogen bonds, ionic interactions). However, traditional self-healing systems mostly rely on direct contact repair mechanisms, which require physical extrusion, heating or solvent penetration to trigger the repair reaction. This type of method has obvious limitations in closed environments, precision devices or deep damage scenarios, and repeated repairs can easily lead to a significant decrease in mechanical properties, making it difficult to meet high strength and high durability requirements.

[0003] For example, the Chinese invention patent with patent number 202310829782 and patent name "A high-strength self-repairing polyurethane infrared shielding material and its preparation method" discloses a method for preparing a high-strength self-repairing polyurethane infrared shielding material, which includes the following steps: 1) weighing raw materials such as nano-gallium tin oxide, dicyclohexylmethane diisocyanate, and polyether polyol; 2) preparing a polyurethane with self-repairing function; 3) dispersing nano-gallium tin oxide in polyurethane and curing it to obtain the high-strength self-repairing polyurethane infrared shielding material. Although the polyurethane infrared shielding material prepared in this patent has a self-repairing function, it relies on a direct contact repair mechanism and requires physical extrusion, heating, or solvent penetration to trigger the repair reaction. Repeated repairs can easily lead to a significant decrease in the mechanical properties of polyurethane, making it difficult to meet the requirements of high strength and high durability. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a non-contact high-strength self-repairing polyurethane material having thermal conductivity, non-contact repair, and the ability to avoid damage, aging, and cracking, and a preparation method thereof.

[0005] To achieve the above objectives, the inventors provide a non-contact method for preparing a high-strength self-healing polyurethane material, which comprises the following steps:

[0006] 1) Weigh the following raw materials according to their amounts:

[0007] 20 parts of hard segment monomer;

[0008] 9 parts of soft segment monomer;

[0009] 4-8 parts of isophthalic acid hydrazide;

[0010] 3) Under a nitrogen atmosphere, the pretreated soft segment monomer is dissolved in organic solvent A, mixed at 50-60° C., and a catalytic amount of dibutyltin dilaurate is added as a catalyst; then, the hard segment monomer is slowly added, and the temperature is raised to 80° C., and the reaction is stirred in a nitrogen atmosphere for 2-4 hours to obtain a polyurethane prepolymer;

[0011] 3) adding isophthalic acid hydrazide to an organic solvent A at 75-85° C., and then dripping the mixture into the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 12-15 hours to obtain a self-healing polyurethane;

[0012] 4) adding MXene to organic solvent A and ultrasonically dispersing the MXene at room temperature to obtain a MXene dispersion; then, under stirring at room temperature, adding the MXene dispersion dropwise to the self-healing polyurethane obtained in step 3) to obtain a self-healing polyurethane / MXene composite dispersion;

[0013] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0014] MXene is a novel two-dimensional material composed of transition metal carbides, nitrides, or carbonitrides. It possesses unique chemical and physical properties and has attracted widespread attention in recent years across a variety of fields. The name MXene derives from its parent material, the MAX phase (e.g., Ti3AlC2), in which the two-dimensional structure of MXene is generated by selectively etching the A-layer elements (e.g., Al).

[0015] The present invention adopts the above-mentioned preparation method, which is simple to operate. The polyurethane is obtained by reaction at 40-45°C, and the operation of MXene dispersion of polyurethane can be carried out at room temperature. That is, the present invention has mild reaction conditions, high production efficiency, and is suitable for large-scale production.

[0016] The present invention adds a chain extender isophthalic acid hydrazide to the polyurethane. There are a large number of amino groups in isophthalic acid hydrazide. A large number of amino groups and carbonyl groups in the polyurethane serve as hydrogen bonding sites, so that the polyurethane has a high density of intermolecular hydrogen bond interaction forces, and introduces a photothermal conversion agent (MXene) into the polyurethane. After absorbing light energy, it is converted into heat energy, locally heating the polyurethane material. The heat energy causes the hydrogen bond network in the polyurethane to dissociate, the molecular chain segments to diffuse again, and the broken interface of the polyurethane is repaired by hydrogen bond recombination. Near-infrared light (NIR) is used to remotely heat the polyurethane to induce hydrogen bond recombination between polyurethane molecules. At room temperature, it only takes 2 minutes to make the polyurethane have a considerable repair efficiency, thereby realizing non-contact repair of polyurethane elastomers. The 3D network structure of MXene can effectively transfer heat, and combined with the efficient photothermal conversion of MXene, the polyurethane elastomer has ideal thermal conductivity. In addition, high-density hydrogen bonds gather at the interface between the polyurethane and the MXene material, giving the flexible composite polyurethane elastomer excellent room temperature self-healing ability and excellent mechanical properties.

[0017] This invention significantly improves the reliability and service life of polyurethane materials through the coordinated design of a non-contact self-healing mechanism and a high-strength structure, providing a new solution for their application in extreme environments and high-end equipment. The technical solution of this invention not only overcomes the performance limitations of existing self-healing materials but also provides new ideas and methods for the development of smart materials.

[0018] Furthermore, the content of the MXene in the non-contact high-strength self-healing polyurethane material is 1-10 wt%.

[0019] Furthermore, the hard segment monomer is one of the following: isophorone diisocyanate or dicyclohexylmethane diisocyanate. Isocyanates, as hard segments, affect the strength and stiffness of polyurethanes. Aromatic isocyanates, due to their rigid aromatic rings, provide polyurethanes prepared from them with stronger hard segment cohesion and higher tensile strength than aliphatic isocyanate-based polyurethanes. However, they exhibit poor resistance to UV degradation and are prone to yellowing. Polyurethanes prepared from isophorone diisocyanate or dicyclohexylmethane diisocyanate are aliphatic and less prone to yellowing, which in turn prevents discoloration in the resulting film.

[0020] Furthermore, the soft segment monomer is one of the following: polytetrahydrofuran with a molecular weight of 2000, polyethylene glycol with a molecular weight of 2000, or polypropylene glycol with a molecular weight of 2000. In the present invention, the molecular weights are all number average molecular weights. Polytetrahydrofuran, polyethylene glycol, and polypropylene glycol are polyether polyols that can be polymerized with isocyanate to form polyurethanes, and the strength of the synthesized polyurethane decreases with the increase of the molecular weight of the polyether polyol, but the flexibility and elongation increase. If a polyether polyol with a molecular weight that is too high is selected, the strength of the prepared film is improved, but the flexibility is reduced, and the self-healing effect is reduced. If a polyether polyol with a molecular weight that is too low is selected, the strength of the prepared film is reduced, but the flexibility is increased, and the self-healing effect is improved. In order to take into account both the strength and flexibility of the prepared film, and the flexibility of the molecular chain is conducive to improving the self-healing effect of the film, the present invention preferably uses a polyether polyol with a molecular weight of 2000.

[0021] Furthermore, the isophthalic acid hydrazide acts as a polyurethane chain extender. The hydrazide groups in isophthalic acid hydrazide react with the -NCO groups in isocyanates to form acyl semicarbazide groups (ASCZ). Therefore, the hard segment of the polymer synthesized from these two compounds is composed of multiple ASCZ groups and carbamate groups, with abundant hydrogen bonds. Under the efficient photothermal conversion of MXene, the hydrogen bond network is dissociated, greatly improving the mechanical strength and self-healing properties of the polyurethane.

[0022] Furthermore, the pretreatment of the soft segment monomer and N,N-dimethylformamide in step 2) is as follows: drying the soft segment monomer or N,N-dimethylformamide under reduced pressure and vacuum at 110° C. to remove moisture.

[0023] Furthermore, the stirring speed in step 2) is 200 r / min, and the stirring speed in step 4) is 200 r / min.

[0024] Furthermore, the organic solvent A is one of the following: N,N-dimethylformamide, N,N-dimethylacetamide.

[0025] The present invention also provides a non-contact high-strength self-healing polyurethane material, which includes MXene and a polyurethane matrix. The MXene is dispersed in the polyurethane matrix as a photothermal filler, and the content of the MXene in the non-contact high-strength self-healing polyurethane material is 1-10wt%.

[0026] Different from the existing technology, the above technical solution has the following advantages:

[0027] 1. Through molecular design, isophthalic acid hydrazide is used as a chain extender, and MXene material is added at the same time to obtain a self-healing polyurethane elastomer with a micro-nano structure and an interfacial hydrogen bond aggregation synergistic structure.

[0028] 2. By adding photothermal conversion MXene materials to self-healing polyurethane, near-infrared light is used to remotely heat and induce the reorganization of hydrogen bonds between polyurethane molecules, thereby achieving non-contact repair of polyurethane elastomers.

[0029] 3. The 3D network structure of MXene can effectively transfer heat. Combined with the efficient photothermal conversion of MXene, the polyurethane elastomer has ideal thermal conductivity.

[0030] 4. The non-contact, high-strength, self-healing polyurethane material provided by the present invention uses less filler and has excellent photothermal and self-healing properties. At the same time, due to the non-contact self-healing method, long-term use does not affect the mechanical properties and processing properties of the polyurethane, greatly extending the service life of the product.

[0031] 5. The preparation method of the present invention has simple process, mild reaction conditions, high production efficiency, and is suitable for large-scale production.

[0032] In summary, the non-contact, high-strength, self-healing polyurethane material of the present invention exhibits a tensile strength exceeding 51.78 MPa, and after self-healing experiments, the tensile strength remains above 45.89 MPa. Therefore, the non-contact, high-strength, self-healing polyurethane material of the present invention retains the high-strength mechanical properties of polyurethane materials, can overcome damage caused by cracking and scratching during use, and extend the material's service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the infrared spectrum of the non-contact high-strength self-healing polyurethane material prepared in Example 1 and Example 2. DETAILED DESCRIPTION

[0034] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0035] Example 1: A method for preparing a non-contact high-strength self-repairing polyurethane material

[0036] A non-contact high-strength self-healing polyurethane material includes MXene and a polyurethane matrix. The MXene is a photothermal filler, the MXene is dispersed in the polyurethane matrix, and the content of MXene in the non-contact high-strength self-healing polyurethane material is 1wt%.

[0037] The preparation method comprises the following steps:

[0038] 1) Weigh the raw materials according to the following molar fractions:

[0039]

[0040] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polytetrahydrofuran (2000 molecular weight) and 29 mmol of N,N-dimethylformamide were added to a four-necked flask and mixed at 50°C until fully dissolved. 0.017 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of dicyclohexylmethane diisocyanate was then slowly added, and the mixture was stirred at 80°C and 200 rpm in a nitrogen atmosphere for 3 hours to obtain a polyurethane prepolymer. The polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide were both pretreated by drying the polytetrahydrofuran (2000 molecular weight) or N,N-dimethylformamide (2000 molecular weight) under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0041] 3) dissolving 6 mmol of isophthalic acid hydrazide in 45 mmol of N,N-dimethylformamide at 80° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 13 hours to obtain a self-healing polyurethane;

[0042] 4) 0.24 g of MXene was added to the remaining N,N-dimethylformamide and ultrasonically dispersed at room temperature to obtain a MXene dispersion; then, the MXene dispersion was dropwise added to the self-healing polyurethane emulsion obtained in step 3) at room temperature and a stirring speed of 200 r / min to prepare a self-healing polyurethane / MXene composite dispersion.

[0043] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0044] Example 2: A method for preparing a non-contact high-strength self-repairing polyurethane material

[0045] A non-contact high-strength self-healing polyurethane material includes MXene and a polyurethane matrix. The MXene is a photothermal filler, the MXene is dispersed in the polyurethane matrix, and the content of MXene in the non-contact high-strength self-healing polyurethane material is 3wt%.

[0046] The preparation method comprises the following steps:

[0047] 1) Weigh the raw materials according to the following molar fractions:

[0048]

[0049] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polytetrahydrofuran (2000 molecular weight) and 29 mmol of N,N-dimethylformamide were added to a four-necked flask and mixed at 50°C until fully dissolved. 0.017 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of dicyclohexylmethane diisocyanate was then slowly added, and the mixture was stirred at 80°C in a nitrogen atmosphere at a stirring speed of 200 r / min for 3 hours to obtain a polyurethane prepolymer. The polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide were both pretreated by drying the polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0050] 3) dissolving 6 mmol of isophthalic acid hydrazide in 45 mmol of N,N-dimethylformamide at 80° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 13 hours to obtain a self-healing polyurethane;

[0051] 4) Add 0.75 g of MXene to the remaining N,N-dimethylformamide and ultrasonically disperse at room temperature to obtain a MXene dispersion; then, at room temperature and a stirring speed of 200 r / min, add the MXene dispersion dropwise to the self-healing polyurethane emulsion obtained in step 3) to prepare a self-healing polyurethane / MXene composite dispersion.

[0052] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0053] Example 3: A method for preparing a non-contact high-strength self-repairing polyurethane material

[0054] A non-contact high-strength self-healing polyurethane material includes MXene and a polyurethane matrix. The MXene is a photothermal filler, the MXene is dispersed in the polyurethane matrix, and the content of MXene in the non-contact high-strength self-healing polyurethane material is 5wt%.

[0055] The preparation method comprises the following steps:

[0056] 1) Weigh the raw materials according to the following molar fractions:

[0057]

[0058] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polytetrahydrofuran (2000 molecular weight) and 29 mmol of N,N-dimethylformamide were added to a four-necked flask and mixed at 50°C until fully dissolved. 0.017 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of dicyclohexylmethane diisocyanate was then slowly added, and the mixture was stirred at 80°C in a nitrogen atmosphere at a stirring speed of 200 r / min for 3 hours to obtain a polyurethane prepolymer. The polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide were both pretreated by drying the polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0059] 3) dissolving 6 mmol of isophthalic acid hydrazide in 45 mmol of N,N-dimethylformamide at 75° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 13 hours to obtain a self-healing polyurethane;

[0060] 4) 1.27 g of MXene was added to the remaining N,N-dimethylformamide and ultrasonically dispersed at room temperature to obtain a MXene dispersion. The MXene dispersion was then added dropwise to the self-healing polyurethane emulsion obtained in step 3) at room temperature and a stirring speed of 200 r / min to prepare a self-healing polyurethane / MXene composite dispersion.

[0061] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0062] Example 4: A method for preparing a non-contact high-strength self-repairing polyurethane material

[0063] A non-contact high-strength self-healing polyurethane material includes MXene and a polyurethane matrix. The MXene is a photothermal filler, the MXene is dispersed in the polyurethane matrix, and the content of MXene in the non-contact high-strength self-healing polyurethane material is 10wt%.

[0064] The preparation method comprises the following steps:

[0065] 1) Weigh the raw materials according to the following molar fractions:

[0066]

[0067] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polytetrahydrofuran (2000 molecular weight) and 29 mmol of N,N-dimethylformamide were added to a four-necked flask and mixed at 50°C until fully dissolved. 0.017 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of dicyclohexylmethane diisocyanate was then slowly added, and the mixture was stirred at 80°C in a nitrogen atmosphere at a stirring speed of 200 r / min for 3 hours to obtain a polyurethane prepolymer. The polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide were both pretreated by drying the polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0068] 3) dissolving 6 mmol of isophthalic acid hydrazide in 45 mmol of N,N-dimethylformamide at 85° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 13 hours to obtain a self-healing polyurethane;

[0069] 4) Add 2.69 g of MXene to the remaining N,N-dimethylformamide and ultrasonically disperse at room temperature to obtain a MXene dispersion; then, at room temperature and a stirring speed of 200 r / min, add the MXene dispersion dropwise to the self-healing polyurethane emulsion obtained in step 3) to prepare a self-healing polyurethane / MXene composite dispersion.

[0070] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0071] Example 5: A method for preparing a non-contact high-strength self-repairing polyurethane material

[0072] A non-contact high-strength self-healing polyurethane material includes MXene and a polyurethane matrix. The MXene is a photothermal filler, the MXene is dispersed in the polyurethane matrix, and the content of MXene in the non-contact high-strength self-healing polyurethane material is 1wt%.

[0073] The preparation method comprises the following steps:

[0074] 1) Weigh the raw materials according to the following molar fractions:

[0075]

[0076] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polyethylene glycol (MW 2000) and 25 mmol of N,N-dimethylacetamide were added to a four-necked flask and mixed at 60°C until fully dissolved. 0.02 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of isophorone diisocyanate was slowly added, and the mixture was stirred at 80°C in a nitrogen atmosphere at a stirring rate of 200 r / min for 2 hours to obtain a polyurethane prepolymer. The 2000 molecular weight polytetrahydrofuran and N,N-dimethylacetamide were pretreated by drying the 2000 molecular weight polyethylene glycol and N,N-dimethylacetamide under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0077] 3) dissolving 8 mmol of isophthalic acid hydrazide in 60 mmol of N,N-dimethylacetamide at 80° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 12 hours to obtain a self-healing polyurethane;

[0078] 4) 0.24 g of MXene was added to the remaining N,N-dimethylacetamide and ultrasonically dispersed at room temperature to obtain a MXene dispersion; then, the MXene dispersion was dropwise added to the self-healing polyurethane emulsion obtained in step 3) at room temperature and a stirring speed of 200 r / min; thereby preparing a self-healing polyurethane / MXene composite dispersion.

[0079] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0080] Example 6: A method for preparing a non-contact high-strength self-repairing polyurethane material

[0081] A non-contact high-strength self-healing polyurethane material includes MXene and a polyurethane matrix. The MXene is a photothermal filler, the MXene is dispersed in the polyurethane matrix, and the content of MXene in the non-contact high-strength self-healing polyurethane material is 1wt%.

[0082] The preparation method comprises the following steps:

[0083] 1) Weigh the raw materials according to the following molar fractions:

[0084]

[0085] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polytetrahydrofuran (2000 molecular weight) and 35 mmol of N,N-dimethylformamide were added to a four-necked flask and mixed at 50°C until fully dissolved. 0.015 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of dicyclohexylmethane diisocyanate was then slowly added, and the mixture was stirred at 80°C in a nitrogen atmosphere at a stirring rate of 200 r / min for 4 hours to obtain a polyurethane prepolymer. The polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide were both pretreated by drying the polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0086] 3) dissolving 4 mmol of isophthalic acid hydrazide in 30 mmol of N,N-dimethylformamide at 80° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 15 hours to obtain a self-healing polyurethane;

[0087] 4) 0.23 g of MXene was added to the remaining N,N-dimethylformamide and ultrasonically dispersed at room temperature to obtain a MXene dispersion; then, the MXene dispersion was dropwise added to the self-healing polyurethane emulsion obtained in step 3) at room temperature and a stirring speed of 200 r / min; thereby preparing a self-healing polyurethane / MXene composite dispersion.

[0088] 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

[0089] Comparative Example

[0090] 1) Weigh the raw materials according to the following molar fractions:

[0091]

[0092] 2) Under a nitrogen atmosphere, 9 mmol of pretreated polytetrahydrofuran (2000 molecular weight) and 29 mmol of N,N-dimethylformamide were added to a four-necked flask and mixed at 50°C until fully dissolved. 0.017 mmol of dibutyltin dilaurate (catalyst) was then added. 20 mmol of isophorone diisocyanate was then slowly added, and the mixture was stirred at 80°C in a nitrogen atmosphere at a stirring rate of 200 r / min for 3 hours to obtain a polyurethane prepolymer. The polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide were both pretreated by drying the polytetrahydrofuran (2000 molecular weight) and N,N-dimethylformamide under reduced pressure and vacuum drying at 110°C for half an hour to fully remove moisture.

[0093] 3) dissolving 6 mmol of isophthalic acid hydrazide in the remaining N,N-dimethylformamide at 80° C. and adding the solution dropwise to the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 13 hours to obtain a self-healing polyurethane;

[0094] 4) pouring the self-repairing polyurethane obtained in step 3) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-repairing polyurethane material.

[0095] The non-contact high-strength self-repairing polyurethane materials prepared in Examples 1 to 6 and the polyurethane materials prepared in the comparative examples were subjected to various performance tests. The conditions for the various performance tests were as follows:

[0096] Tensile test before and after self-repair: According to GB / T 528-2009, the sample was cut into dumbbell-shaped specimens and the tensile strength and elongation at break were tested using a universal tensile testing machine at a speed of 100 mm / min. Each sample was measured three times and the average value was taken. A 2 mm deep crack was cut in the middle of the dumbbell-shaped specimen and a 200 mW cm -2 The fracture site of the sample is irradiated with near-infrared (NIR) light for a certain period of time. The repaired sample is subjected to a tensile test. The self-healing efficiency (SE) is calculated as follows:

[0097] SE=б2 / б1×100%

[0098] б2 is the tensile strength of the healed sample, and б1 is the tensile strength of the original sample.

[0099] According to the above detection method, the above detection was performed on the non-contact high-strength self-healing polyurethane materials prepared in Examples 1 to 6 and the polyurethane materials prepared in the comparative example. The specific monitoring data are shown in Table 1.

[0100] Table 1 Comparison of test data of products prepared in various embodiments

[0101]

[0102]

[0103] As shown in Table 1, the non-contact, high-strength, self-healing polyurethane material prepared by the present invention has an increased tensile strength and an increased elongation at break relative to the comparative example due to the addition of the MXene material, meeting the material's use conditions. The comparative example had no repair performance under near-infrared light repair conditions, while the non-contact, high-strength, self-healing polyurethane material prepared by the present invention can achieve a high repair efficiency under near-infrared light irradiation for 2 minutes. According to the self-repair experiment, the products of Examples 1 to 6 all have excellent tensile strength and self-repair efficiency.

[0104] Therefore, the non-contact high-strength self-repairing polyurethane material of the present invention retains the mechanical properties of the polyurethane material, can overcome the losses caused by cracking and scratching of the polyurethane material during use, and extend the service life of the material.

[0105] The infrared spectra of the polyurethane materials prepared in Example 1 and Example 2 are shown in FIG. Figure 1 , 2264cm -1 There is no absorption peak at 3323cm, indicating that the -NCO group in the system has been completely reacted. -1 and 1536cm -1 The absorption peaks at 2854cm are the stretching vibration and bending vibration of the NH bond in carbamate. -1 and 2935cm -1 The peaks at 1701cm are the CH symmetric and asymmetric stretching vibration peaks of the methylene groups in the polyurethane molecular chain. -1 The peak at 1101 cm is the C=O stretching vibration absorption peak of the carbamate group. -1 The peaks correspond to the asymmetric and symmetric stretching of the COC groups in PTMG.

[0106] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described herein, or equivalent structural or equivalent process transformations made using the contents of the present invention's specification and drawings, and direct or indirect application of the above technical solutions to other related technical fields, are all included in the scope of patent protection of the present invention.

Claims

1. A non-contact method for preparing a high-strength self-repairing polyurethane material, characterized in that: It includes the following steps: 1) Weigh the following raw materials according to their amounts: 20 parts of hard segment monomer; 9 parts of soft segment monomer; 4-8 parts of isophthalic acid hydrazide; 2) Under a nitrogen atmosphere, the pretreated soft segment monomer is dissolved in organic solvent A, mixed at 50-60° C., and a catalytic amount of dibutyltin dilaurate is added as a catalyst; then, the hard segment monomer is slowly added, and the temperature is raised to 80° C., and the reaction is stirred in a nitrogen atmosphere for 2-4 hours to obtain a polyurethane prepolymer; 3) adding isophthalic acid hydrazide to an organic solvent A at 75-85° C., and then dripping the mixture into the polyurethane prepolymer obtained in step 2), reacting at 40-45° C. for 12-15 hours to obtain a self-healing polyurethane; 4) adding MXene to organic solvent A and ultrasonically dispersing the MXene at room temperature to obtain a MXene dispersion; then, under stirring at room temperature, adding the MXene dispersion dropwise to the self-healing polyurethane obtained in step 3) to obtain a self-healing polyurethane / MXene composite dispersion; 5) pouring the self-healing polyurethane / MXene composite dispersion obtained in step 4) into a polytetrafluoroethylene mold and curing it at room temperature to obtain the non-contact high-strength self-healing polyurethane material.

2. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The content of the MXene in the non-contact high-strength self-healing polyurethane material is 1-10 wt%.

3. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The hard segment monomer is one of the following: isophorone diisocyanate or dicyclohexylmethane diisocyanate.

4. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The soft segment monomer is one of the following: polytetrahydrofuran with a molecular weight of 2000, polyethylene glycol with a molecular weight of 2000, or polypropylene glycol with a molecular weight of 2000.

5. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The isophthalic acid hydrazide is used as a polyurethane chain extender.

6. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The pretreatment of the soft segment monomer and N,N-dimethylformamide in step 2) is as follows: the soft segment monomer or N,N-dimethylformamide is dried under reduced pressure and vacuum at 110° C. to remove moisture.

7. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The stirring speed in step 2) is 200 r / min, and the stirring speed in step 4) is 200 r / min.

8. The method for preparing a non-contact high-strength self-repairing polyurethane material according to claim 1, characterized in that: The organic solvent A is one of the following: N,N-dimethylformamide and N,N-dimethylacetamide.

9. The non-contact high-strength self-repairing polyurethane material prepared by the preparation method according to any one of claims 1 to 8 is characterized in that : It includes MXene and a polyurethane matrix, wherein the MXene is dispersed in the polyurethane matrix as a photothermal filler, and the content of the MXene in the non-contact high-strength self-healing polyurethane material is 1-10wt%.

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