High-temperature-resistant high-resilience self-repairing polyurethane elastomer and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant high-resilience self-repairing polyurethane elastomer and a preparation method thereof, and relates to the technical field of self-repairing. The preparation method comprises the following steps: taking polytetrahydrofuran glycol, vacuumizing and dehydrating; introducing nitrogen, adding isophorone diisocyanate and dibutyltin dilaurate, and carrying out a reaction so as to obtain a polyurethane prepolymer; taking a polyurethane prepolymer, introducing nitrogen, adding a chain extender A and a chain extender B, stirring, adding the mixed solution, and stirring; adding a metal salt solution and N, N-dimethylaniline, and uniformly mixing; putting the mixture into a polytetrafluoroethylene mold, reacting, vacuumizing, removing bubbles, curing, cooling and demolding to obtain the high-temperature-resistant high-resilience self-repairing polyurethane elastomer. Amino groups of 2, 6-diaminopyridine react with isocyanate groups of the polyurethane prepolymer, and 2, 6-diaminopyridine and metal ions in the metal salt solution are coordinated to form metal coordination bonds, so that the high-temperature resistance, resilience and self-repairing performance of the polyurethane elastomer are improved.

Description

Technical Field

[0001] This invention relates to the field of self-healing technology, specifically to a high-temperature resistant, high-resilience self-healing polyurethane elastomer and its preparation method. Background Technology

[0002] Polyurethane elastomers, an organic polymer material, are widely used in the automotive, aerospace, electronic devices and industrial manufacturing fields. In these applications, polyurethane materials are required to have excellent high-temperature resistance, resilience and self-healing properties.

[0003] Polyurethane elastomers are often exposed to high-temperature environments during processing and application. For example, as seals in the aerospace field, they are located near engines or heating components, requiring polyurethane elastomers to maintain excellent performance even at high temperatures.

[0004] During material use, microcracks and scratches are prone to occur. To fundamentally solve this problem and improve the service life of polyurethane elastomers, self-healing materials can be introduced into the polyurethane elastomers during the initial processing stage to achieve self-healing. Among these, the metal ligand method of self-healing achieves self-repair through reversible dynamic coordination bonds formed between metal ions in the polymer and organic macromolecular ligands. Due to the strong interaction forces and high-temperature resistance of metal coordination bonds, self-healing elastomers with cross-linked coordination bonds have become a crucial class in the field of self-healing materials research.

[0005] Currently, the variety of self-healing polyurethane elastomers is still insufficient, and balancing their strength and self-healing properties remains a major technical challenge. Summary of the Invention

[0006] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a high-temperature resistant, high-resilience, self-healing polyurethane elastomer, and another purpose of this invention is to provide a method for preparing the elastomer.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for preparing a high-temperature resistant, high-resilience, self-healing polyurethane elastomer involves taking a polyurethane prepolymer, adding chain extender A, chain extender B and a mixed solution for chain extension, then adding a metal salt solution and N,N-dimethylaniline, mixing evenly and then curing into a film to obtain the self-healing polyurethane elastomer. The chain extender A is any one of 4,4'-diaminodiphenyl disulfide, p-hydroxydiphenyl disulfide, bis(2-amino-3-methylphenyl) disulfide, cystamine, and aminoethyl sulfide; The chain extender B is any one of aminopyridine, 5,5'-diamino-2,2'-bipyridine, 3,5-diaminobenzoic acid, and 2,4-diamino-6-hydroxypyrimidine; The mixed solution is prepared by taking methyl methacrylate, styrene, benzoyl peroxide, and modified carbon nanotubes, and mixing them evenly at a temperature of 35-45℃ to obtain a mixed solution.

[0008] Further, polytetrahydrofuran diol was taken, vacuumed, and dehydrated; nitrogen gas was introduced, and isophorone diisocyanate and dibutyltin dilaurate were added, and the reaction was carried out to obtain polyurethane prepolymer.

[0009] Furthermore, the metal salt solution is prepared by adding the metal salt to N,N-dimethylformamide and stirring until completely dissolved at a temperature of 35-45℃ to obtain the metal salt solution.

[0010] Furthermore, the metal salt is any one of zinc chloride, ferric chloride, copper chloride, lanthanum trifluoromethanesulfonate, and aluminum acetylacetonate.

[0011] Furthermore, the modified carbon nanotubes are obtained by compounding hydroxyl carbon nanotubes and carbon nanotubes-polymethyl methacrylate.

[0012] Further, the preparation method of the modified carbon nanotubes is as follows: multi-walled carbon nanotubes are added to concentrated nitric acid, sonicated for 20-30 min, refluxed for 3-5 h at 115-125℃, diluted, filtered, pH adjusted with deionized water, vacuum dried, ground, and sieved to obtain hydroxyl carbon nanotubes; potassium persulfate and sodium dodecyl sulfate are added to deionized water, methyl methacrylate is added, and reacted for 1-2 h at 75-85℃, hydroxyl carbon nanotubes, potassium persulfate, and sodium dodecyl sulfate are added, reacted for 30-40 min, centrifuged, dried, extracted, and dried to obtain carbon nanotube-polymethyl methacrylate; hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate are taken at a mass ratio of (0.8-1.2):(0.8-1.2), mixed evenly, ground, and sieved to obtain modified carbon nanotubes.

[0013] Further, the mass ratio of methyl methacrylate, styrene, benzoyl peroxide, and modified carbon nanotubes is (13-14):(13-14):(0.26-0.28):(1-1.5).

[0014] Furthermore, the mass ratio of chain extender A to chain extender B is (5-6):(0.8-1.2).

[0015] Furthermore, the pH value is adjusted to 6.8-7.2.

[0016] The high-temperature resistant, high-resilience, self-healing polyurethane elastomer prepared by the aforementioned method.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. A polyurethane elastomer is prepared by adding polytetrahydrofuran diol as a soft segment, isophorone diisocyanate as a hard segment, and dibutyltin dilaurate as a catalyst to form a polyurethane prepolymer. The polyurethane prepolymer is then taken and 4,4'-diaminodiphenyl disulfide and 2,6-diaminopyridine are added as chain extenders. The amino group of 4,4'-diaminodiphenyl disulfide reacts with the isocyanate group of the polyurethane prepolymer to introduce dynamic disulfide bonds. When heated to 80-120℃, the disulfide bonds undergo homolytic cleavage, generating sulfur free radicals that recombine and achieve self-repair. The amino group of 2,6-diaminopyridine reacts with the isocyanate group of the polyurethane prepolymer, and 2,6-diaminopyridine coordinates with metal ions in the metal salt solution to form metal coordination bonds. When damaged, these bonds reorganize at the damaged site through thermal motion at room temperature. Furthermore, the metal coordination bonds have high dissociation energy and are not easily pyrolyzed, thus improving the high-temperature resistance, resilience, and self-healing properties of the polyurethane elastomer. Two chain extenders synergistically improve the self-healing properties of the polyurethane elastomer through different mechanisms of action and introduce rigid benzene rings into the polyurethane molecular chain, thereby improving the mechanical properties and high-temperature resistance of the polyurethane elastomer.

[0018] 2. By adding benzoyl peroxide as an initiator and N,N-dimethylaniline as a accelerator, methyl methacrylate and styrene undergo free radical polymerization, and the polyurethane prepolymer further undergoes polymerization. The two polymers interpenetrate and entangle with each other to obtain a polyurethane elastomer with a semi-interpenetrating network structure. Among them, methyl methacrylate and styrene form a polymethyl methacrylate-polystyrene polymer through free radical polymerization, which has a high glass transition temperature. It penetrates and entangles in the polyurethane network, providing a rigid skeleton for the polyurethane network. When the polyurethane elastomer is subjected to impact, the polymethyl methacrylate-polystyrene polymer supports the polyurethane network, improving the mechanical properties and high-temperature resistance of the polyurethane elastomer.

[0019] 3. Prepare modified carbon nanotubes by compounding hydroxyl carbon nanotubes and carbon nanotubes-polymethyl methacrylate; wherein, under the strong oxidation of concentrated nitric acid, hydroxyl and carboxyl groups are introduced on the surface of carbon nanotubes. The hydroxyl groups on the surface of hydroxyl carbon nanotubes react with the isocyanate groups of polyurethane prepolymer to form covalent bonds. The hydroxyl carbon nanotubes are then grafted onto the polyurethane network through covalent bonds. Using potassium persulfate as an initiator and sodium dodecyl sulfate as an emulsifier, methyl methacrylate undergoes a free radical graft polymerization reaction to form polymethyl methacrylate-coated carbon nanotubes, resulting in carbon nanotube-polymethyl methacrylate. The polymethyl methacrylate shell and the polymethyl methacrylate-polystyrene polymer have excellent interfacial compatibility. Through modification, the dispersibility and compatibility of carbon nanotubes in polyurethane elastomers are improved. Carbon nanotubes have excellent toughness and can be used as reinforcing fillers, which is beneficial to improving the mechanical properties, high-temperature resistance, and resilience of polyurethane elastomers. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The sources and types of substances involved in this invention are not particularly limited, and exemplary examples include: Polytetrahydrofuran diol (p-code AL644506058669) was supplied by Greenlink (Jining) Chemical Technology Co., Ltd.; isophorone diisocyanate (p-code hnouj-12) was supplied by Wuhan Kanos Technology Co., Ltd.; dibutyltin dilaurate (p-code M33151) was supplied by Shanghai Mairui Biochemical Technology Co., Ltd.; multi-walled carbon nanotubes (p-code AM-MWCNT-N-03) were supplied by Zhejiang Yamei Nanotechnology Co., Ltd.; potassium persulfate (p-code CFEQ-4-120046-0500) was supplied by Shanghai Anpu Experimental Technology Co., Ltd.; sodium dodecyl sulfate (p-code WD0194) was supplied by Hubei Wande Chemical Co., Ltd.; and methyl methacrylate (p-code C0835510223) was supplied by Nan... The following products are provided: Styrene (CG26) from Beijing Chemical Reagent Co., Ltd.; Benzoyl peroxide (C0794510323) from Nanjing Chemical Reagent Co., Ltd.; Zinc chloride (M25750) from Shanghai Mairui Biochemical Technology Co., Ltd.; N,N-Dimethylformamide (007) from Yangzhou Fenghuangdao Chemical Co., Ltd.; 4,4'-Diaminodiphenyl disulfide (M24379) from Shanghai Mairui Biochemical Technology Co., Ltd.; 2,6-Diaminopyridine (S42571) from Shanghai Yuanye Biotechnology Co., Ltd.; and N,N-Dimethylaniline (HY121-69-7) from Changzhou Hongyu Chemical Co., Ltd.

[0022] Example 1 A method for preparing a high-temperature resistant, high-resilience, self-healing polyurethane elastomer, specifically comprising: Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it at 110℃ for 2 hours; then introduce nitrogen gas and add 33g of isophorone diisocyanate and 0.06g of dibutyltin dilaurate at 80℃, and react for 3 hours to obtain polyurethane prepolymer.

[0023] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 20min, reflux for 3h at 115℃, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.05g potassium persulfate and 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 75℃ for 1h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 30min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 0.8:1.2, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0024] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 13g of methyl methacrylate, 13g of styrene, 0.26g of benzoyl peroxide, and 1g of modified carbon nanotubes. Mix them evenly at 35℃ and sonicate for 20min to obtain a mixed solution. Take 3g of zinc chloride and add it to 10mL of N,N-dimethylformamide. Stir at 35℃ until completely dissolved to obtain a metal salt solution. S2: Take the polyurethane prepolymer, introduce nitrogen gas, add 32g of 4,4'-diaminodiphenyl disulfide and 5g of 2,6-diaminopyridine at 80℃, stir for 2min, add the mixed solution, stir for 3min, add the metal salt solution and 0.1mL of N,N-dimethylaniline, mix evenly; place in a polytetrafluoroethylene mold, react for 24h at 25℃, vacuum to remove bubbles, cure for 10h at 80℃, cool, demold, and obtain a high-temperature resistant, high-resilience self-healing polyurethane elastomer.

[0025] Example 2 A method for preparing a high-temperature resistant, high-resilience, self-healing polyurethane elastomer, specifically comprising: Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it for 2 hours at 110℃. Then, introduce nitrogen gas and add 35g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate at 80℃. React for 3 hours to obtain polyurethane prepolymer.

[0026] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 25min, reflux at 120℃ for 4h, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.05g potassium persulfate and 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 80℃ for 1.5h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 35min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 1:1, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0027] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 13.5g of methyl methacrylate, 13.5g of styrene, 0.27g of benzoyl peroxide, and 1.3g of modified carbon nanotubes, mix them evenly at 40℃, and sonicate for 25min to obtain a mixed solution; take 4g of zinc chloride and add it to 10mL of N,N-dimethylformamide, and stir until completely dissolved at 40℃ to obtain a metal salt solution; S2: Take the polyurethane prepolymer, introduce nitrogen gas, add 33g of 4,4'-diaminodiphenyl disulfide and 6g of 2,6-diaminopyridine at 80℃, stir for 3min, add the mixed solution, stir for 4min, add the metal salt solution and 0.15mL of N,N-dimethylaniline, mix evenly; place in a polytetrafluoroethylene mold, react for 24h at 25℃, vacuum to remove bubbles, cure for 10h at 80℃, cool, demold, and obtain a high-temperature resistant, high-resilience self-healing polyurethane elastomer.

[0028] Example 3 A method for preparing a high-temperature resistant, high-resilience, self-healing polyurethane elastomer, specifically comprising: Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it for 2 hours at 110℃. Then, introduce nitrogen gas and add 37g of isophorone diisocyanate and 0.1g of dibutyltin dilaurate at 80℃. React for 3 hours to obtain polyurethane prepolymer.

[0029] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 30min, reflux at 125℃ for 5h, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.05g potassium persulfate and 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 85℃ for 2h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 40min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 1.2:0.8, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0030] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 14g of methyl methacrylate, 14g of styrene, 0.28g of benzoyl peroxide, and 1.5g of modified carbon nanotubes. Mix them evenly at 45℃ and sonicate for 30min to obtain a mixed solution. Take 5g of zinc chloride and add it to 10mL of N,N-dimethylformamide. Stir at 45℃ until completely dissolved to obtain a metal salt solution. S2: Take the polyurethane prepolymer, introduce nitrogen gas, add 34g of 4,4'-diaminodiphenyl disulfide and 7g of 2,6-diaminopyridine at 80℃, stir for 4min, add the mixed solution, stir for 5min, add the metal salt solution and 0.2mL of N,N-dimethylaniline, mix evenly; place in a polytetrafluoroethylene mold, react for 24h at 25℃, vacuum to remove bubbles, cure for 10h at 80℃, cool, demold, and obtain a high-temperature resistant, high-resilience self-healing polyurethane elastomer.

[0031] Comparative Example 1 4,4'-diaminodiphenyl disulfide was not added; otherwise, refer to Example 2.

[0032] Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it for 2 hours at 110℃. Then, introduce nitrogen gas and add 35g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate at 80℃. React for 3 hours to obtain polyurethane prepolymer.

[0033] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 25min, reflux at 120℃ for 4h, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.05g potassium persulfate and 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 80℃ for 1.5h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 35min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 1:1, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0034] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 13.5g of methyl methacrylate, 13.5g of styrene, 0.27g of benzoyl peroxide, and 1.3g of modified carbon nanotubes, mix them evenly at 40℃, and sonicate for 25min to obtain a mixed solution; take 4g of zinc chloride and add it to 10mL of N,N-dimethylformamide, and stir until completely dissolved at 40℃ to obtain a metal salt solution; S2: Take polyurethane prepolymer, introduce nitrogen gas, add 6g of 2,6-diaminopyridine at 80℃, stir for 3min, add mixed solution, stir for 4min, add metal salt solution and 0.15mL of N,N-dimethylaniline, mix evenly; place in polytetrafluoroethylene mold, react at 25℃ for 24h, vacuum, remove bubbles, cure at 80℃ for 10h, cool, demold, and obtain high temperature resistant, high resilience, self-healing polyurethane elastomer.

[0035] Comparative Example 2 Without adding 2,6-diaminopyridine, refer to Example 2 for the rest.

[0036] Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it for 2 hours at 110℃. Then, introduce nitrogen gas and add 35g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate at 80℃. React for 3 hours to obtain polyurethane prepolymer.

[0037] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 25min, reflux at 120℃ for 4h, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.05g potassium persulfate and 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 80℃ for 1.5h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 35min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 1:1, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0038] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 13.5g of methyl methacrylate, 13.5g of styrene, 0.27g of benzoyl peroxide, and 1.3g of modified carbon nanotubes, mix them evenly at 40℃, and sonicate for 25min to obtain a mixed solution; take 4g of zinc chloride and add it to 10mL of N,N-dimethylformamide, and stir until completely dissolved at 40℃ to obtain a metal salt solution; S2: Take the polyurethane prepolymer, introduce nitrogen gas, add 33g of 4,4'-diaminodiphenyl disulfide at 80℃, stir for 3min, add the mixed solution, stir for 4min, add the metal salt solution and 0.15mL of N,N-dimethylaniline, mix evenly; place in a polytetrafluoroethylene mold, react for 24h at 25℃, vacuum to remove bubbles, cure for 10h at 80℃, cool, demold, and obtain a high-temperature resistant, high-resilience self-healing polyurethane elastomer.

[0039] Comparative Example 3 Styrene was not added; otherwise, refer to Example 2.

[0040] Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it for 2 hours at 110℃. Then, introduce nitrogen gas and add 35g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate at 80℃. React for 3 hours to obtain polyurethane prepolymer.

[0041] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 25min, reflux at 120℃ for 4h, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.05g potassium persulfate and 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 80℃ for 1.5h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 35min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 1:1, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0042] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 13.5g of methyl methacrylate, 0.27g of benzoyl peroxide, and 1.3g of modified carbon nanotubes, mix them evenly at 40℃, and sonicate for 25min to obtain a mixed solution; take 4g of zinc chloride and add it to 10mL of N,N-dimethylformamide, and stir until completely dissolved at 40℃ to obtain a metal salt solution; S2: Take the polyurethane prepolymer, introduce nitrogen gas, add 33g of 4,4'-diaminodiphenyl disulfide and 6g of 2,6-diaminopyridine at 80℃, stir for 3min, add the mixed solution, stir for 4min, add the metal salt solution and 0.15mL of N,N-dimethylaniline, mix evenly; place in a polytetrafluoroethylene mold, react for 24h at 25℃, vacuum to remove bubbles, cure for 10h at 80℃, cool, demold, and obtain a high-temperature resistant, high-resilience self-healing polyurethane elastomer.

[0043] Comparative Example 4 Without adding potassium persulfate, refer to Example 2 for the rest.

[0044] Step 1: Preparation of polyurethane prepolymer Take 100g of polytetrahydrofuran diol, evacuate it, and dehydrate it for 2 hours at 110℃. Then, introduce nitrogen gas and add 35g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate at 80℃. React for 3 hours to obtain polyurethane prepolymer.

[0045] Step 2: Preparation of modified carbon nanotubes S1: Take 1g of multi-walled carbon nanotubes and add them to 100mL of concentrated nitric acid. Sonicate for 25min, reflux at 120℃ for 4h, dilute, filter, adjust the pH to 7 with deionized water, vacuum dry, grind, and sieve to obtain hydroxyl carbon nanotubes. S2: Add 0.1g sodium dodecyl sulfate to 100mL of deionized water, add 5g methyl methacrylate, and react at 80℃ for 1.5h. Then add 0.5g hydroxyl carbon nanotubes, 0.05g potassium persulfate, and 0.05g sodium dodecyl sulfate, react for 35min, centrifuge, dry, extract, and dry to obtain carbon nanotube-polymethyl methacrylate. S3: Take hydroxyl carbon nanotubes and carbon nanotube-polymethyl methacrylate at a mass ratio of 1:1, mix them evenly, grind them, and sieve them to obtain modified carbon nanotubes.

[0046] Step 3: Preparation of high-temperature resistant, high-resilience, self-healing polyurethane elastomer S1: Take 13.5g of methyl methacrylate, 13.5g of styrene, 0.27g of benzoyl peroxide, and 1.3g of modified carbon nanotubes, mix them evenly at 40℃, and sonicate for 25min to obtain a mixed solution; take 4g of zinc chloride and add it to 10mL of N,N-dimethylformamide, and stir until completely dissolved at 40℃ to obtain a metal salt solution; S2: Take the polyurethane prepolymer, introduce nitrogen gas, add 33g of 4,4'-diaminodiphenyl disulfide and 6g of 2,6-diaminopyridine at 80℃, stir for 3min, add the mixed solution, stir for 4min, add the metal salt solution and 0.15mL of N,N-dimethylaniline, mix evenly; place in a polytetrafluoroethylene mold, react for 24h at 25℃, vacuum to remove bubbles, cure for 10h at 80℃, cool, demold, and obtain a high-temperature resistant, high-resilience self-healing polyurethane elastomer.

[0047] experiment: The mechanical properties and self-healing properties of the polyurethane elastomers prepared in Examples 1-3 and Comparative Examples 1-4 were measured.

[0048] Take the above-mentioned polyurethane elastomer, cut it vertically in the middle, attach the cut, press for 2 minutes, and repair it for 24 hours at a temperature of 80℃ to obtain a repaired sample; take the elastomer and the repaired sample, and use a UTM universal testing machine to determine the tensile strength. The sample size is 30mm×5mm×0.3mm, the gauge length is 10mm, and the tensile rate is 10mm / min. Obtain the initial tensile strength and the repaired tensile strength, and calculate the self-healing efficiency. The above experiments were completed, and the results are shown in Table 1 below: Table 1

[0049] Conclusion: Based on the analysis of the above experimental data, the self-healing polyurethane elastomers prepared in Examples 1-3 of this invention have higher tensile strength and self-healing efficiency, and better mechanical and self-healing properties; while the polyurethane elastomers prepared in Comparative Examples 1-4 have lower tensile strength and self-healing efficiency, and poorer mechanical and self-healing properties.

[0050] Comparative analysis of Comparative Example 1 (without 4,4'-diaminodiphenyl disulfide) and Example 2 shows that the amino group of 4,4'-diaminodiphenyl disulfide reacts with the isocyanate group of the polyurethane prepolymer to introduce dynamic disulfide bonds. When heated to 80-120°C, the disulfide bonds undergo homolytic cleavage, generating sulfur free radicals that recombine and achieve self-repair. Furthermore, a rigid benzene ring is introduced into the polyurethane molecular chain, improving the mechanical properties of the polyurethane elastomer.

[0051] Comparative analysis of Comparative Example 2 (without 2,6-diaminopyridine) and Example 2 shows that the amino group of 2,6-diaminopyridine reacts with the isocyanate group of the polyurethane prepolymer, and 2,6-diaminopyridine coordinates with metal ions in the metal salt solution to form metal coordination bonds. When damaged, these bonds reorganize at the damaged site through thermal motion at room temperature. Furthermore, the metal coordination bonds have high dissociation energy and are not easily pyrolyzed, thus improving the high-temperature resistance, resilience, and self-healing properties of the polyurethane elastomer. Introducing rigid benzene rings into the polyurethane molecular chain also improves the mechanical properties of the polyurethane elastomer.

[0052] Comparative analysis of Comparative Example 3 (without styrene) and Example 2 shows that with the addition of benzoyl peroxide as an initiator and N,N-dimethylaniline as a accelerator, methyl methacrylate and styrene undergo free radical polymerization, and the polyurethane prepolymer further undergoes polymerization. The two polymers interpenetrate and entangle with each other, resulting in a polyurethane elastomer with a semi-interpenetrating network structure. Methyl methacrylate and styrene form a polymethyl methacrylate-polystyrene polymer through free radical polymerization, which has a high glass transition temperature. This polymer penetrates and entangles within the polyurethane network, providing a rigid framework for the polyurethane network. When the polyurethane elastomer is subjected to impact, the polymethyl methacrylate-polystyrene polymer supports the polyurethane network, improving the mechanical properties of the polyurethane elastomer.

[0053] Comparative analysis of Comparative Example 4 (without potassium persulfate) and Example 2 shows that using potassium persulfate as an initiator and sodium dodecyl sulfate as an emulsifier, methyl methacrylate undergoes a free radical graft polymerization reaction to form polymethyl methacrylate-coated carbon nanotubes, resulting in carbon nanotube-polymethyl methacrylate. The polymethyl methacrylate shell and the polymethyl methacrylate-polystyrene polymer exhibit excellent interfacial compatibility. Modification improves the dispersibility and compatibility of carbon nanotubes in polyurethane elastomers. Carbon nanotubes possess excellent toughness and can be used as reinforcing fillers, which is beneficial for improving the mechanical properties, high-temperature resistance, and resilience of polyurethane elastomers.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A process for the preparation of a high temperature resistant, high resilience, self-repairing polyurethane elastomer, characterized in that, The polyurethane prepolymer is taken, chain extenders A, chain extenders B and a mixed solution are added for chain extension, then a metal salt solution and N,N-dimethyl aniline are added, and a film is formed after uniform mixing and solidification, so that the self-repairing polyurethane elastomer is obtained; The chain extender A is any one of 4,4'-diamino diphenyl disulfide, p-hydroxy diphenyl disulfide, bis(2-amino-3-methylphenyl) disulfide, cystamine and aminoethyl sulfide; The chain extender B is any one of amino pyridine, 5,5'-diamino-2,2'-bipyridine, 3,5-diamino benzoic acid and 2,4-diamino-6-hydroxy pyrimidine; The preparation method of the mixed solution is as follows: methyl methacrylate, styrene, dibenzoyl peroxide and modified carbon nanotubes are uniformly mixed at a temperature of 35-45 DEG C to obtain the mixed solution.

2. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 1, wherein, The polyurethane prepolymer is obtained by vacuumizing and dehydrating polytetrahydrofuran diol, introducing nitrogen, adding isophorone diisocyanate and dibutyl tin dilaurate and reacting.

3. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 1, wherein, The preparation method of the metal salt solution is as follows: a metal salt is added into N,N-dimethyl formamide, and stirred until completely dissolved at a temperature of 35-45 DEG C to obtain the metal salt solution.

4. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 3, wherein, The metal salt is any one of zinc chloride, iron chloride, copper chloride, lanthanum triflate and aluminum acetylacetonate.

5. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 1, wherein, The modified carbon nanotube is obtained by compounding hydroxyl carbon nanotubes and carbon nanotube-poly methyl methacrylate.

6. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 1 or 5, wherein, The preparation method of the modified carbon nanotube is as follows: multi-walled carbon nanotubes are added into concentrated nitric acid, ultrasonically treated for 20-30 min, refluxed at a temperature of 115-125 DEG C for 3-5 h, diluted, filtered, adjusted to a pH value by using deionized water, vacuum dried, ground, sieved to obtain hydroxyl carbon nanotubes; potassium persulfate and sodium dodecyl sulfate are added into deionized water, methyl methacrylate is added, reacted at a temperature of 75-85 DEG C for 1-2 h, hydroxyl carbon nanotubes, potassium persulfate and sodium dodecyl sulfate are added, reacted for 30-40 min, centrifuged, dried, extracted and dried to obtain carbon nanotube-poly methyl methacrylate; the hydroxyl carbon nanotubes and the carbon nanotube-poly methyl methacrylate are taken according to a mass ratio of (0.8-1.2):(0.8-1.2), uniformly mixed, ground and sieved to obtain the modified carbon nanotube.

7. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 1, wherein, The mass ratio of the methyl methacrylate, styrene, dibenzoyl peroxide and modified carbon nanotube is (13-14):(13-14):(0.26-0.28):(1-1.5).

8. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 1, wherein, The mass ratio of the chain extender A and the chain extender B is (5-6):(0.8-1.2).

9. The process for the preparation of high temperature resistant, high resilience, self-healing polyurethane elastomer as claimed in claim 6, wherein, The pH value is adjusted to 6.8-7.

2.

10. A high-temperature-resistant and high-resilience self-repairing polyurethane elastomer prepared by the method according to any one of claims 1-9.

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