阅读说明：本技术 一种聚氨酯弹性体及其制备方法 (Polyurethane elastomer and preparation method thereof ) 是由 徐康茗 胡乔曼 于 2021-10-25 设计创作，主要内容包括：一种聚氨酯弹性体,其化学结构如下：,其中,X为二异氰酸酯；m=13或26；n=0～0.5。本发明以GL和HMIC作为扩链剂复合作用,制备的聚氨酯弹性体所得聚氨酯弹性体可同步实现良好力学性能及快速自修复性。弹性体的拉伸强度达到27.24 MPa,断裂伸长率范围为1450～2044%,韧性最高达到211.94 MJ/m～(3),在400～800 nm可见光范围内透光率≥90%,试样拉伸至原长6.5倍可在30 s内快速回复至原长,0.7 mm试样被拉伸至原长5倍情况下也未被锐物刺穿,在80℃下修复3 h,修复效率大于等于80%。(A polyurethane elastomer has the following chemical structure: wherein X is diisocyanate; m =13 or 26; n =0~ 0.5. According to the invention, GL and HMIC are used as chain extenders for composite action, and the polyurethane elastomer obtained from the prepared polyurethane elastomer can synchronously realize good mechanical properties and quick self-repairability. The tensile strength of the elastomer reaches 27.24MPa, the elongation at break range is 1450-2044%, and the toughness reaches 211.94MJ/m at most 3 The light transmittance is more than or equal to 90% in a visible light range of 400-800 nm, the sample can be quickly recovered to the original length within 30s after being stretched to 6.5 times of the original length, the sample with the thickness of 0.7mm is not punctured by a sharp object even when being stretched to 5 times of the original length, the sample is repaired for 3 hours at the temperature of 80 ℃, and the repairing efficiency is more than or equal to 80%.)

1. A polyurethane elastomer characterized by the following chemical structure:

wherein X is diisocyanate; m =13 or 26; n =0~ 0.5.

2. A method for preparing the polyurethane elastomer according to claim 1, wherein: the preparation method comprises the preparation of a prepolymer and the synthesis of an elastomer, and specifically comprises the steps of firstly reacting long-chain diol with diisocyanate under the action of an organic tin catalyst to prepare the prepolymer, and reacting a chain extender 5- (2-hydroxyethyl) -6-methyl-2-aminouracil (HMIC) and a chain extender 3- (2- (2, 3-dihydroxypropyl) thio) ethoxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (GL) with the prepolymer to synthesize the polyurethane elastomer, wherein the GL has a chemical structural formula as follows:

。

3. the method for producing a polyurethane elastomer according to claim 2, wherein: mixing triethylene glycol bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (AO-70) and NaOH, dissolving in distilled water, and adding into the mixture₂Refluxing for 6-8 h in atmosphere, and then extracting, precipitating and drying to obtain 3- (3- (tert-butyl alcohol)4-hydroxy-5-methylphenyl) propanedioic Acid (AC), then mixing AC, ethylene glycol monoallyl ether, cyclohexane and p-toluenesulfonic acid in N₂Reflux reaction is carried out under the atmosphere to prepare a solid product ES, and the solid product ES is mixed with 2, 2-dimethoxy-2-phenylacetophenone, tetrahydrofuran and 1-thioglycerol to carry out ultraviolet irradiation to prepare the product.

4. A process for producing a polyurethane elastomer according to claim 2 or 3, wherein: the long-chain diol is one of polytetrahydrofuran with average molecular weight of 1000 and 2000.

5. The process for producing a polyurethane elastomer according to any one of claims 2 to 4, wherein: the diisocyanate is one of hexamethylene diisocyanate, dicyclohexylmethane 4,4 '-diisocyanate and isophorone diisocyanate, and dicyclohexylmethane 4,4' -diisocyanate is preferred.

6. The process for producing a polyurethane elastomer according to any one of claims 2 to 5, wherein: the molar ratio of the diisocyanate to the long-chain diol to the chain extender is 2-2.05: 1:1, and the molar ratio of the HMIC to the GL in the chain extender is 0: 2-1: 1.

7. The method for producing a polyurethane elastomer according to claim 6, wherein: the prepolymer is prepared by dehydrating polytetrahydrofuran at 110-120 ℃ and 40-70 Pa for 2h, then cooling to 85 ℃, adding diisocyanate, and reacting with N₂Stirring for 1h at 220-250 rpm under the environment, then reducing the temperature to 80 ℃, adding the catalyst, and continuously stirring for 3 h.

8. The method of claim 7, wherein the polyurethane elastomer is prepared by the following steps: and the elastomer is synthesized by adding HMIC into the prepared prepolymer, stirring and reacting for 0.5h at 250-300 rpm, then adding GL dissolved in N, N-dimethylformamide, continuously stirring for 3h, curing for 24h at 80 ℃ after the reaction is finished, and finally drying at 70 ℃.

9. A polyurethane elastomer, characterized in that its structure is:

wherein n is 0-0.5.

10. The process for producing a polyurethane elastomer according to claim 9, which comprises the steps of:

the method comprises the following steps: preparation of GL

(1) Dissolving AO-70 and NaOH in distilled water, and dissolving in N₂Refluxing for 6-8 h under an atmosphere, extracting for 2 times by using dichloromethane, titrating the solution by using hydrochloric acid until the pH value is 3 to generate a white precipitate suspension, standing for 12h, filtering and collecting a precipitate, washing to be neutral, and drying to obtain 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) malonic Acid (AC), wherein the molar volume ratio of AO-70, NaOH and distilled water is 0.1mol: 0.8-1 mol:266 mL;

(2) dispersing the mixture of AC and ethylene glycol monoallyl ether in cyclohexane, adding p-toluenesulfonic acid, and reacting in N₂Refluxing and reacting for 6-8 h in an atmosphere, washing the solution obtained by the reaction for 3 times by using a saturated sodium bicarbonate solution, performing rotary evaporation to remove cyclohexane to obtain an oily product, standing at room temperature for 48h to obtain a solid product, namely 3- (allyloxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (ES), wherein the molar volume ratio of AC, ethylene glycol monoallyl ether and cyclohexane is 0.275mol:0.25mol:150mL, and the dosage of p-toluenesulfonic acid is 2-2.5 wt% of the ethylene glycol monoallyl ether;

(3) mixing the solid product ES with 2, 2-dimethoxy-2-phenylacetophenone and tetrahydrofuran, and filling N₂Continuing for 10min, adding 1-thioglycerol, mixing, performing irradiation reaction for 25-40 min by using 365nm ultraviolet light, finally performing rotary evaporation to remove tetrahydrofuran to obtain an oily product, dissolving the oily product in dichloromethane, washing with distilled water for 5 times, drying with anhydrous sodium sulfate, standing24h, filtering to remove sodium sulfate, and performing rotary evaporation to remove dichloromethane to obtain an oily product GL, wherein the molar volume ratio of ES, 1-thioglycerol and tetrahydrofuran is 0.05-0.06 mol:0.06mol:40mL, and the using amount of 2, 2-dimethoxy-2-phenylacetophenone is 0.5-0.6 wt% of ES;

step two: preparation of a prepolymer

Taking Polytetrahydrofuran (PTMEG) with the average molecular weight of 1000, drying and dewatering for 2 hours at the temperature of 110-120 ℃ and the vacuum degree of 40-70 Pa, reducing the temperature to 85 ℃, adding dicyclohexylmethane 4,4' -diisocyanate (HMDI), and adding into N₂Stirring and reacting for 1h at 220-250 rpm in the atmosphere, reducing the temperature to 80 ℃, dropwise adding a catalyst of dibutyltin dilaurate (DBTDL), and reacting in N₂Continuously stirring and reacting for 3 hours at 220-250 rpm in the atmosphere to obtain a prepolymer, wherein the molar ratio of dicyclohexylmethane 4,4' -diisocyanate to polytetrahydrofuran is 2-2.05: 1, and the dosage of dibutyltin dilaurate is 0.5-1 wt% of long-chain diol;

step three: synthesis of polyurethane elastomer

(1) Adding a solid chain extender HMIC into the prepolymer prepared in the second step, stirring and reacting for 0.5h at 250-300 rpm, then adding a chain extender GL dissolved in N, N-Dimethylformamide (DMF), and continuously stirring and reacting for 3h at 250-300 rpm, wherein the molar ratio of the total chain extender used in the step (2) to the polytetrahydrofuran used in the step (1) is 1:1, the molar ratio of HMIC to CL in the chain extender is 0: 2-1: 1, and the molar volume ratio of GL to DMF is 1-2 mmol:2 mL;

(2) after the reaction is finished, pouring the obtained solution into a mold, placing the mold at 80 ℃ for curing reaction for 24 hours, and then carrying out vacuum drying at 70 ℃.

Technical Field

The invention relates to the technical field of materials, and particularly relates to a polyurethane elastomer and a preparation method thereof.

Background

The polyurethane-based self-repairing material has the capability of repairing self cracks and recovering the initial performance, and has great application potential in the aspects of flexible electronics, soft robots, protective coatings, medical instruments and the like because the material can improve the stability of products, prolong the service life of the products and reduce the loss of raw materials. However, in practical application, the polymer molecular chain required by the rapid repair performance has high hardness, high entanglement and crystallization capabilities, so that the molecular chain diffusion and exchange capabilities are reduced, the rapid repair performance and the excellent mechanical properties are in mutual contradiction, the mechanical properties and the rapid self-repair performance of the material are difficult to be considered, and the industrial application of the polyurethane-based self-repair material is greatly limited.

In order to solve the problem, researchers prepare polyurethane elastomers with different structures by introducing dynamic non-covalent bonds or dynamic covalent bonds into a polyurethane hard segment from the viewpoint of polyurethane structure design. Among them, hydrogen bonds are widely introduced due to their easily regulated bond energy and moderate repair conditions. The mechanical and self-repairing performances of the polyurethane-based self-repairing material are adjusted through the forms of strong and weak hydrogen bonds, multiphase hydrogen bonds, dynamic hard segment micro-regions and the like, but the synchronous promotion of good mechanical performance and quick self-repairing performance is always a great challenge.

Disclosure of Invention

The invention aims to provide a polyurethane elastomer which has the advantages of high strength, high toughness, high quick self-repairing performance, high transparency and the like.

The second object of the present invention is a process for producing the above polyurethane elastomer.

The purpose of the invention is realized by the following technical scheme:

a polyurethane elastomer characterized by the following chemical structure:

wherein X is diisocyanate; m is 13 or 26; n is 0 to 0.5.

The preparation method of the polyurethane elastomer is characterized by comprising the following steps: the preparation method comprises the steps of preparing a prepolymer and synthesizing an elastomer, specifically, reacting long-chain diol and diisocyanate under the action of a catalyst to prepare the prepolymer, and reacting 5- (2-hydroxyethyl) -6-methyl-2-aminouracil (HMIC) and 3- (2- (2, 3-dihydroxypropyl) thio) ethoxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (GL) as a chain extender with the prepolymer to synthesize the polyurethane elastomer, wherein the GL has a chemical structural formula as follows:

further, the long-chain diol is one of polytetrahydrofuran having an average molecular weight of 1000 and 2000, and polytetrahydrofuran having an average molecular weight of 1000 is preferable.

Further, the diisocyanate is one of hexamethylene diisocyanate, dicyclohexylmethane 4,4 '-diisocyanate, and isophorone diisocyanate, and dicyclohexylmethane 4,4' -diisocyanate is preferable.

Further, the molar ratio of the diisocyanate to the long-chain diol to the chain extender is 2-2.05: 1:1, and the molar ratio of the HMIC to the GL in the chain extender is 0: 2-1: 1.

Further, the catalyst is an organic tin catalyst, specifically one of dibutyltin dioctoate and dibutyltin dilaurate, preferably dibutyltin dilaurate, and the dosage of the catalyst is 0.5-1 wt% of the long-chain diol.

Further, the prepolymer is prepared by dehydrating polytetrahydrofuran at 110-120 ℃ and 40-70 Pa for 2h, cooling to 85 ℃, adding diisocyanate, and reacting with N₂Stirring for 1h at 220-250 rpm in the environment to improve the reaction activity, then reducing the temperature to 80 ℃, adding a catalyst, and continuously stirring for 3h to prevent the crosslinking in the catalytic process from causing agglomeration and even failing to generate a target product.

Further, the elastomer is synthesized by adding HMIC into the prepared prepolymer, stirring and reacting for 0.5h at 250-300 rpm, then adding GL dissolved in N, N-dimethylformamide, continuously stirring for 3h, curing for 24h at 80 ℃ after the reaction is finished, and finally drying at 70 ℃.

Further, the molar volume ratio of GL to N, N-dimethylformamide is 1-2 mmol:2 mL.

The HMIC and the GL are used as chain extenders for combined use, the HMIC effectively improves the strength of the elastomer, and the GL has the effects of increasing the toughness of the elastomer and accelerating the repair speed.

The preparation method of the chain extender GL is characterized by comprising the following steps: mixing triethylene glycol bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (AO-70) and NaOH, dissolving in distilled water, and adding N₂Refluxing for 6-8 h in atmosphere, extracting, precipitating and drying to obtain 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) malonic Acid (AC), and mixing AC, ethylene glycol monoallyl ether, cyclohexane and p-toluenesulfonic acid in N₂And (3) carrying out reflux reaction under the atmosphere to prepare a solid product ES, mixing the solid product ES with 2, 2-dimethoxy-2-phenylacetophenone, tetrahydrofuran and 1-thioglycerol, and carrying out ultraviolet irradiation to obtain a product GL.

Further, the molar volume ratio of AO-70 to NaOH to distilled water is 0.1mol:0.8 to 1mol:800 mL.

Furthermore, the molar volume ratio of the AC to the ethylene glycol monoallyl ether to the cyclohexane is 0.275mol: 0.25-0.28 mol:150mL, and the amount of the p-toluenesulfonic acid is 2-2.5 wt% of the ethylene glycol monoallyl ether.

Furthermore, the molar volume ratio of the ES, the 1-thioglycerol and the tetrahydrofuran is 0.05mol: 0.05-0.06 mol:40mL, and the using amount of the 2, 2-dimethoxy-2-phenylacetophenone is 0.5-0.6 wt% of the ES.

Further, the ultraviolet irradiation is carried out by mixing ES with 2, 2-dimethoxy-2-phenylacetophenone and tetrahydrofuran, and charging into N₂Continuing for 10min, adding 1-thioglycerol, mixing, and carrying out irradiation reaction for 25-40 min by adopting 365nm ultraviolet light.

Further, the precipitation is that hydrochloric acid is dripped into the extracted solution until the pH value is 3, white precipitation suspension is generated, and the white precipitation suspension is filtered and collected after standing for 12 hours.

A polyurethane elastomer, characterized in that its structure is:

wherein n is 0-0.5.

The preparation method of the polyurethane elastomer is characterized by comprising the following steps:

the method comprises the following steps: preparation of GL

(1) Dissolving AO-70 and NaOH in distilled water, and dissolving in N₂Refluxing for 6-8 h under an atmosphere, extracting for 2 times by using dichloromethane, titrating the solution by using hydrochloric acid until the pH value is 3 to generate a white precipitate suspension, standing for 12h, filtering and collecting the precipitate, washing to be neutral, and drying to obtain 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) malonic Acid (AC), wherein the molar volume ratio of AO-70, NaOH and distilled water is 0.1mol: 0.8-1 mol:266 mL;

(2) dispersing the mixture of AC and ethylene glycol monoallyl ether in cyclohexane, adding p-toluenesulfonic acid, and reacting in N₂Refluxing and reacting for 6-8 h in an atmosphere, washing the solution obtained by the reaction for 3 times by using a saturated sodium bicarbonate solution, carrying out rotary evaporation to remove cyclohexane to obtain an oily product, standing at room temperature for 48h to obtain a solid product, namely 3- (allyloxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (ES), wherein the molar volume ratio of AC to ethylene glycol monoallyl ether to cyclohexane is 0.275mol:0.25mol:150mL, and the dosage of p-toluenesulfonic acid is 2-2.5 wt% of the ethylene glycol monoallyl ether;

(3) mixing the solid product ES with 2, 2-dimethoxy-2-phenylacetophenone and tetrahydrofuran, and filling N₂Continuing for 10min, adding 1-thioglycerol, mixing, carrying out irradiation reaction for 25-40 min by using 365nm ultraviolet light, finally carrying out rotary evaporation to remove tetrahydrofuran to obtain an oily product, dissolving the oily product in dichloromethane, washing with distilled water for 5 times, drying with anhydrous sodium sulfate, standing for 24h, filtering to remove sodium sulfate, and carrying out rotary evaporation to remove dichloromethane to obtain an oily product GL, wherein the molar volume ratio of ES, 1-thioglycerol and tetrahydrofuran is 0.05-0.06 mol:0.06mol:40mL, and 2, 2-dimethyl furan is usedThe dosage of the oxy-2-phenylacetophenone is 0.5 to 0.6 weight percent of the ES;

step two: preparation of a prepolymer

Taking Polytetrahydrofuran (PTMEG) with the average molecular weight of 1000, drying and dewatering for 2 hours at the temperature of 110-120 ℃ and the vacuum degree of 40-70 Pa, reducing the temperature to 85 ℃, adding dicyclohexylmethane 4,4' -diisocyanate (HMDI), and adding into N₂Stirring and reacting for 1h at 220-250 rpm in the atmosphere, reducing the temperature to 80 ℃, dropwise adding a catalyst of dibutyltin dilaurate (DBTDL), and reacting in N₂Continuously stirring and reacting for 3 hours at 220-250 rpm in the atmosphere to obtain a prepolymer, wherein the molar ratio of dicyclohexylmethane 4,4' -diisocyanate to polytetrahydrofuran is 2-2.05: 1, and the dosage of dibutyltin dilaurate is 0.5-1 wt% of long-chain diol;

step three: synthesis of polyurethane elastomer

(1) Adding a solid chain extender HMIC into the prepolymer prepared in the second step, stirring and reacting for 0.5h at 250-300 rpm, then adding a chain extender GL dissolved in N, N-Dimethylformamide (DMF), and continuously stirring and reacting for 3h at 250-300 rpm, wherein the molar ratio of the total chain extender used in the step (2) to the polytetrahydrofuran used in the step (1) is 1:1, the molar ratio of HMIC to CL in the chain extender is 0: 2-1: 1, and the molar volume ratio of GL to DMF is 1-2 mmol:2 mL;

(2) after the reaction is finished, pouring the obtained solution into a mold, placing the mold at 80 ℃ for curing reaction for 24 hours, and then carrying out vacuum drying at 70 ℃.

In the invention, a unit formed by combining HMIC is an HM unit, a unit formed by combining GL is an HP unit, and the prepared polyurethane elastomer is marked as PU-HM-HP. In the HM cell, HMIC binds to rigid HMDI to form quadruple strong Hydrogen Bonds (HBs), acting as strong physical crosslinks in the elastomer, the HP units, which are attached to the ends of the long side chains, form a single weak hydrogen bond that is reconnected to each other, accelerating the repair of the elastomer, and due to the longer side chains, excessive entanglement of the chains in the elastomer is also reduced, meanwhile, the HP unit has strengthened relative movement, shows weak binding energy and strong exchange property, and is synergistically regulated through strong and weak balance by an HB network formed by strong HBs in a main chain and weak HBs in a side chain, the polyurethane elastomer has excellent mechanical properties and quick repairing performance, and the polyurethane elastomer synthesized by the reaction of HMIC and GL with the prepolymer prepared from any long-chain diol, diisocyanate and catalyst under the above conditions can achieve the excellent technical effect.

The invention has the following technical effects:

the invention takes GL and HMIC as chain extender for composite action, has obvious toughening effect, and can synchronously realize good mechanical property and quick self-repairability. The tensile strength of the elastomer reaches 27.24MPa, the elongation at break range is 1450-2044%, and the toughness reaches 211.94MJ/m at most³The light transmittance is more than or equal to 90% in a visible light range of 400-800 nm, the sample can be quickly recovered to the original length within 30s after being stretched to 6.5 times of the original length, the sample with the thickness of 0.7mm is not punctured by a sharp object even if being stretched to 5 times of the original length, the sample is repaired for 3 hours at the temperature of 80 ℃, and the repairing efficiency is more than or equal to 80%. The polyurethane elastomer prepared by the method is worthy of market popularization and application.

Drawings

FIG. 1: GL nuclear magnetic hydrogen and infrared spectrograms prepared in example 1.

FIG. 2: the nuclear magnetic hydrogen spectrogram and the infrared spectrogram of the HMIC are shown in the invention.

FIG. 3: the synthetic route of the polyurethane elastomer of the invention is shown schematically.

FIG. 4: nuclear magnetic hydrogen spectra of polyurethane elastomers prepared in examples 1 and 6 of the present invention.

FIG. 5: infrared spectra of polyurethane elastomers prepared in inventive examples 1-6.

FIG. 6: the tensile strength and elongation at break of the polyurethane elastomers prepared in examples 1-6 are shown.

FIG. 7: graphs of the change in toughness of the polyurethane elastomers prepared in examples 1-6.

FIG. 8: graph of the notched fracture energy for the polyurethane elastomers prepared in examples 1-6.

FIG. 9: the polyurethane elastomers prepared in examples 1-6 were plotted for repair efficiency at different temperatures and different times.

FIG. 10: graphs of the transmittance change in the visible light range for the polyurethane elastomers prepared in examples 1-6.

Detailed Description

The present invention is described in detail below by way of examples, it should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and those skilled in the art can make some insubstantial modifications and adaptations to the present invention based on the above-described disclosure.

Sources of chemicals used in the present invention:

guanidine carbonate, ethyl acetoacetate, α -acetyl γ -butyrolactone, triethylamine, ethylene glycol monoallyl ether, 1-thioglycerol, 2-dimethoxy-2-acetophenone, hexamethylene diisocyanate, polytetramethylene ether glycol (PTMEG, Mn ═ 1000g/mol), and dibutyl dilaurate (DBTDL) were purchased from alatin chemicals ltd. (China). Triethylene glycol bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (AO-70) was obtained from Beijing addition Assistant research institute (China). Dicyclohexylmethane 4,4' -diisocyanate (HMDI) was supplied by wanhua chemical group ltd (china). Absolute ethanol, sodium hydroxide, dichloromethane, hydrochloric acid, p-toluenesulfonic acid, cyclohexane, sodium bicarbonate, tetrahydrofuran, anhydrous sodium sulfate, Dimethylformamide (DMF) were purchased from kyotolong chemical agents ltd (china). One week prior to use, DMF was dehydrated with activated 4A molecular sieves for at least 1 hour.

The HMIC and the GL are adopted as chain extenders to prepare the polyurethane elastomer, and the structural formula of the polyurethane elastomer is as follows:

in the formula, n is 0-0.5, and the polyurethane elastomer is marked as PU-HMa-HP10-a according to the usage molar ratio of HMIC and GL, wherein a is 10 n.

The method for synthesizing HMIC used in the invention is as follows:

mixing alpha-acetyl gamma-butyrolactone, guanidine carbonate, triethylamine and absolute ethyl alcohol, and performing reflux reaction for 20 hours, wherein the dosage relationship of the substances is that the alpha-acetyl gamma-butyrolactone: guanidine carbonate: triethylamine: 0.1 mol/0.2 mol/100 mL of anhydrous ethanol. After the reaction is finished, carrying out suction filtration under reduced pressure to obtain a yellow solid crude product, washing the crude product for 3 times by using absolute ethyl alcohol, dissolving the crude product in distilled water to form a suspension, titrating the suspension to the pH value of 7.00 by using dilute hydrochloric acid, carrying out suction filtration under reduced pressure on the neutral suspension, and drying to obtain a white solid product, namely HMIC. The NMR spectrum and IR spectrum are shown in FIG. 2(a) and FIG. 2(b), respectively.

Example 1

The preparation method of the polyurethane elastomer PU-HM0-HP10 comprises the following steps:

the method comprises the following steps: preparation of GL

(1) Dissolving AO-70 and NaOH in distilled water, and dissolving in N₂Refluxing for 8h under the atmosphere, extracting for 2 times by using dichloromethane, titrating the solution by using hydrochloric acid until the pH value is 3 to generate white precipitate suspension, standing for 12h, filtering and collecting precipitate, washing to be neutral, and drying to obtain 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) malonic Acid (AC), wherein the molar volume ratio of AO-70, NaOH and distilled water is 0.1mol:0.8mol:266 mL;

(2) dispersing the mixture of AC and ethylene glycol monoallyl ether in cyclohexane, adding p-toluenesulfonic acid, and reacting in N₂Refluxing and reacting for 8h in the atmosphere, washing the solution obtained by the reaction for 3 times by using a saturated sodium bicarbonate solution, performing rotary evaporation to remove cyclohexane to obtain an oily product, standing at room temperature for 48h to obtain a solid product, namely 3- (allyloxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (ES), wherein the molar volume ratio of AC, ethylene glycol monoallyl ether and cyclohexane is 0.275mol:0.25mol:150mL, and the dosage of p-toluenesulfonic acid is 2 wt% of the ethylene glycol monoallyl ether;

(3) mixing the solid product ES with 2, 2-dimethoxy-2-phenylacetophenone and tetrahydrofuran, and filling N₂Continuing for 10min, adding 1-thioglycerol, mixing, performing irradiation reaction for 30min with 365nm ultraviolet light, removing tetrahydrofuran by rotary evaporation to obtain oily product, dissolving the oily product in dichloromethane, washing with distilled water for 5 times, drying with anhydrous sodium sulfate, standing for 24hFiltering to remove sodium sulfate, and performing rotary evaporation to remove dichloromethane to obtain an oily product GL, wherein the molar volume ratio of ES, 1-thioglycerol and tetrahydrofuran is 0.05mol:0.06mol:40mL, and the using amount of 2, 2-dimethoxy-2-phenylacetophenone is 0.5 wt% of ES;

step two: preparation of a prepolymer

Collecting 20mol of Polytetrahydrofuran (PTMEG) with average molecular weight of 1000, drying at 120 deg.C under 60Pa for 2h to remove water, reducing the temperature to 85 deg.C, adding 40mol of dicyclohexylmethane 4,4' -diisocyanate (HMDI), and adding N₂Stirring and reacting at 250rpm for 1h under the atmosphere, reducing the temperature to 80 ℃, and dropwise adding dibutyltin dilaurate (DBTDL) accounting for 0.5 wt% of polytetrahydrofuran in N₂Continuously stirring and reacting for 3h at 250rpm in the atmosphere to obtain a prepolymer;

step three: synthesis of polyurethane elastomer

(1) Adding 20mmol of chain extender GL dissolved in 20mLN, N-Dimethylformamide (DMF) into the prepolymer prepared in the second step, and continuously stirring at 300rpm for reaction for 3 hours, wherein the molar volume ratio of GL to DMF is 1-2 mmol:2 mL;

(2) after the reaction is finished, pouring the obtained solution into a mold, placing the mold at 80 ℃ for curing reaction for 24 hours, and then carrying out vacuum drying at 70 ℃.

The GL prepared in example 1 was characterized by nuclear magnetic resonance, in particular by dissolving it in anhydrous deuterated chloroform and recording it on a Bruker Avance III 400 spectrometer (Bruker Daltonics, Germany) in the form of a nuclear magnetic resonance spectrum (1H NMR, 400 Hz). The chemical structure was determined by recording the infrared spectrum of the sample by means of a Fourier infrared spectrometer, the GL NMR spectrum and the IR spectrum being shown in FIG. 1 (a) and FIG. 1 (b), respectively.

The polyurethane elastomer prepared by the embodiment has the fracture growth rate of 1536.2461% + -114.1037 and the toughness of 12.296 + -0.044 MJ/m²The fracture energy of the notch is 1.811 +/-0.284, and the stress repair efficiency of the notch in repair at 80 ℃ for 2h is 126.02% +/-10.03.

Example 2

The preparation method of the polyurethane elastomer PU-HM1-HP9 comprises the following steps:

the method comprises the following steps: preparation of GL

(1) Dissolving AO-70 and NaOH in distilled water, and dissolving in N₂Refluxing for 8h under the atmosphere, extracting for 2 times by using dichloromethane, titrating the solution by using hydrochloric acid until the pH value is 3 to generate white precipitate suspension, standing for 12h, filtering and collecting precipitate, washing to be neutral, and drying to obtain 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) malonic Acid (AC), wherein the molar volume ratio of AO-70, NaOH and distilled water is 0.1mol:0.9mol:266 mL;

(2) dispersing the mixture of AC and ethylene glycol monoallyl ether in cyclohexane, adding p-toluenesulfonic acid, and reacting in N₂Refluxing and reacting for 8h in the atmosphere, washing the solution obtained by the reaction for 3 times by using a saturated sodium bicarbonate solution, performing rotary evaporation to remove cyclohexane to obtain an oily product, standing at room temperature for 48h to obtain a solid product, namely 3- (allyloxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (ES), wherein the molar volume ratio of AC, ethylene glycol monoallyl ether and cyclohexane is 0.275mol:0.26mol:150mL, and the dosage of p-toluenesulfonic acid is 2.5wt% of the ethylene glycol monoallyl ether;

(3) mixing the solid product ES with 2, 2-dimethoxy-2-phenylacetophenone and tetrahydrofuran, and filling N₂Continuing for 10min, adding 1-thioglycerol, mixing, carrying out irradiation reaction for 30min by using 365nm ultraviolet light, finally carrying out rotary evaporation to remove tetrahydrofuran to obtain an oily product, dissolving the oily product in dichloromethane, washing the oily product with distilled water for 5 times, drying the oily product with anhydrous sodium sulfate, standing for 24h, filtering to remove the sodium sulfate, and carrying out rotary evaporation to remove the dichloromethane to obtain an oily product GL, wherein the molar volume ratio of ES, 1-thioglycerol and tetrahydrofuran is 0.05mol:0.04mol:40mL, and the dosage of 2, 2-dimethoxy-2-phenylacetophenone is 0.6wt% of ES;

step two: preparation of a prepolymer

Collecting 20mmol of Polytetrahydrofuran (PTMEG) with average molecular weight of 1000, drying at 110 deg.C under 40Pa for 2 hr to remove water, reducing the temperature to 85 deg.C, adding 41mmol of dicyclohexylmethane 4,4' -diisocyanate (HMDI), and adding N₂Stirring and reacting for 1h at 220rpm under the atmosphere, reducing the temperature to 80 ℃, and dropwise adding dibutyltin dilaurate (DBTDL) accounting for 1 wt% of polytetrahydrofuran in N₂Continuously stirring and reacting for 3 hours at 220rpm under the atmosphere,obtaining a prepolymer;

step three: synthesis of polyurethane elastomer

(1) Adding 2mmol of solid chain extender HMIC into the prepolymer prepared in the second step, stirring and reacting for 0.5h at 250rpm, then adding 18mmol of chain extender GL dissolved in 20mLN, N-Dimethylformamide (DMF), and continuing stirring and reacting for 3h at 250 rpm;

(2) after the reaction is finished, pouring the obtained solution into a mold, placing the mold at 80 ℃ for curing reaction for 24 hours, and then carrying out vacuum drying at 70 ℃.

Example 3

The preparation method of the polyurethane elastomer PU-HM2-HP8 comprises the following steps:

the method comprises the following steps: preparation of GL

(1) Dissolving AO-70 and NaOH in distilled water, and dissolving in N₂Refluxing for 8h under the atmosphere, extracting for 2 times by using dichloromethane, titrating the solution by using hydrochloric acid until the pH value is 3 to generate white precipitate suspension, standing for 12h, filtering and collecting precipitate, washing to be neutral, and drying to obtain 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) malonic Acid (AC), wherein the molar volume ratio of AO-70, NaOH and distilled water is 0.1mol:1mol:266 mL;

(2) dispersing the mixture of AC and ethylene glycol monoallyl ether in cyclohexane, adding p-toluenesulfonic acid, and reacting in N₂Refluxing and reacting for 8h in the atmosphere, washing the solution obtained by the reaction for 3 times by using a saturated sodium bicarbonate solution, performing rotary evaporation to remove cyclohexane to obtain an oily product, standing at room temperature for 48h to obtain a solid product, namely 3- (allyloxy) propyl 3- (3- (tert-butyl) -4-hydroxy-5-methylphenyl) propionate (ES), wherein the molar volume ratio of AC, ethylene glycol monoallyl ether and cyclohexane is 0.275mol:0.28mol:150mL, and the dosage of p-toluenesulfonic acid is 2.2 wt% of the ethylene glycol monoallyl ether;

(3) mixing the solid product ES with 2, 2-dimethoxy-2-phenylacetophenone and tetrahydrofuran, and filling N₂Continuing for 10min, adding 1-thioglycerol, mixing, performing irradiation reaction for 30min with 365nm ultraviolet light, removing tetrahydrofuran by rotary evaporation to obtain oily product, dissolving the oily product in dichloromethane, washing with distilled water for 5 times, drying with anhydrous sodium sulfate, standing for 24h,filtering to remove sodium sulfate, and performing rotary evaporation to remove dichloromethane to obtain an oily product GL, wherein the molar volume ratio of ES, 1-thioglycerol and tetrahydrofuran is 0.05mol:0.05mol:40mL, and the using amount of 2, 2-dimethoxy-2-phenylacetophenone is 0.55 wt% of ES;

step two: preparation of a prepolymer

Collecting 20mmol Polytetrahydrofuran (PTMEG) with average molecular weight of 1000, drying at 115 deg.C under 70Pa for 2 hr to remove water, cooling to 85 deg.C, adding 40mmol dicyclohexylmethane 4,4' -diisocyanate (HMDI), and adding N₂Stirring and reacting at 230rpm for 1h under the atmosphere, reducing the temperature to 80 ℃, and dropwise adding dibutyltin dilaurate (DBTDL) accounting for 0.8 wt% of polytetrahydrofuran in N₂Continuously stirring and reacting for 3h at 230rpm under the atmosphere to obtain a prepolymer;

step three: synthesis of polyurethane elastomer

(1) Adding 4mmol of solid chain extender HMIC into the prepolymer prepared in the second step, stirring and reacting for 0.5h at 280rpm, then adding 16mmol of chain extender GL dissolved in 20mLN, N-Dimethylformamide (DMF), and continuing stirring and reacting for 3h at 280 rpm;

(2) after the reaction, the reaction mixture was aged at 80 ℃ for 24 hours, followed by vacuum drying at 70 ℃.

Example 4

Preparation of polyurethane elastomer PU-HM3-HP7, compared with example 1, 6mmol of solid chain extender HMIC is added in step three (2), the reaction is stirred at 250rpm for 0.5h, then 14mmol of chain extender GL dissolved in 20mLN, N-Dimethylformamide (DMF) is added, the reaction is continued at 250rpm for 3h, and the rest steps are the same as example 1

Example 5

Preparation of polyurethane elastomer PU-HM4-HP6, compared with example 1, 8mmol of solid chain extender HMIC was added to step three (2), and the reaction was stirred at 250rpm for 0.5h, then 12mmol of chain extender GL dissolved in 20mL of N-Dimethylformamide (DMF) was added, and the reaction was continued at 250rpm for 3h, and the rest of the procedure was the same as example 1.

Example 6

Preparation of polyurethane elastomer PU-HM5-HP5, compared with example 1, 10mmol of solid chain extender HMIC was added to step three (2), and the reaction was stirred at 250rpm for 0.5h, then 10mmol of chain extender GL dissolved in 20mL of N-Dimethylformamide (DMF) was added, and the reaction was continued at 250rpm for 3h, and the rest of the procedure was the same as example 1.

The tensile strength of PU-HM5-HP5 is 27.237 +/-1.051 MPa, the elongation at break is 1831.124 +/-95.457%, and the toughness is 211.935 +/-12.957 MJ/m³. The super-normal toughness is beneficial to avoiding the formation of cracks and prolonging the service life.

Structural characterization:

1. molecular weight and polydispersity index (PDI)

Through detection, the average molecular weight of the polyurethane elastomer prepared by the invention is 61-91 kDa, and the polydispersity index is about 1.98.

2. Nuclear magnetic characterization and infrared characterization

The PU-HM-HP prepared in example 1 and example 5 was dissolved in anhydrous deuterated chloroform, respectively, and the nuclear magnetic resonance spectrum (1H NMR, 400Hz) was recorded on a Bruker Avance III 400 spectrometer (Bruker Daltonics, Germany) with a nuclear magnetic resonance hydrogen spectrum as shown in FIG. 4 and its infrared spectrum by a Fourier infrared spectrometer with an infrared spectrum as shown in FIG. 5. Thereby determining the structural formula thereof.

3. And (3) testing mechanical properties:

(1) tensile test

The notched PU-HM4-HP6 was subjected to a tensile test, stretched 8 times its original length without breaking, which is also attributed to the introduction of GL side chains in the HP unit, which enhances the toughness of the elastomer, the presence of side chains which weakens entanglement, and the modulation of the strong and weak effect of the Hydrogen Bond (HB) network formed by strong hydrogen bonds in the HM unit and weak hydrogen bonds in the HP unit. As the HM/HP molar ratio increased, the fracture energy of the PU-HM-HP system gradually increased, as shown in FIG. 8. In particular, the breaking energies of PU-HM4-HP6 and PU-HM5-HP5 were 13.798. + -. 0.184 KJ/m²And 16.698 + -0.641 KJ/m²The result shows that the polyurethane elastomer prepared by the invention has good anti-tearing performance. The tensile strength and toughness of the polyurethane elastomers prepared in the respective examples are shown in fig. 6 and 7, respectively. Preparation of poly (arylene sulfide) by using chain extender HMIC aloneWhen the polyurethane elastomer is used, the toughness is 42.692 +/-6.722 MJ/m²The toughness of the polyurethane elastomer prepared using GL alone was 12.296 + -0.044 MJ/m²The toughness of the polyurethane elastomer prepared by the two composite materials can reach 212.436 +/-1.457 MJ/m²。

(2) Rebound and puncture resistance testing

The 0.7mm thick PU-HM-HP specimen was drawn into a shape of 650% elongation, recovering almost completely from 650% elongation within 30 seconds, the 0.7mm thick specimen was not even pierced until the elongation reached 500%. PU-HM-HP has good recoverable deformation recovery and excellent puncture resistance.

2. Repair performance testing

The polyurethane elastomer with the notch was repaired at 25 ℃ and 80 ℃ with the repair efficiency as shown in fig. 9. As the HM/HP molar ratio increases, the increase in the green tensile strength results in a rapid decrease in repair efficiency at room temperature. For high-temperature self-repair (80 ℃), samples from PU-HM0-HP10 to PU-HM3-HP7 show higher repair efficiency (> 92%) after 2 hours of repair, and the repair efficiency is in a descending trend, so that the addition of GL improves the self-repair capability of the polyurethane elastomer and accelerates the repair speed. The process of reciprocal reconnection by weak Hydrogen Bonds (HBs) dominates faster elastic recovery, whereas strong HBs exhibit weak kinetics, requiring more time or more energy to fully recover. The repair efficiency in the present invention is defined as the ratio between healing and original tensile strength for accurate assessment.

As is well known, the repair process goes through five steps: (a) surface rearrangement, (b) surface treatment, (c) wetting, (d) diffusion and (e) randomization, wherein diffusion is the most critical step of repair. For a PU-HM-HP system, weak HBs are introduced into a side chain, so that not only is chain entanglement of a soft domain weakened, but also a soft effect is generated on a strong constraint hard domain, and chain diffusion is promoted, so that the elastomer can realize quick self-repairing. PU-HM4-HP6 exhibits balanced mechanical properties and self-healing properties. Through the cooperation of four strong HBs in the main chain and a single weak HBs in the side chain, the mechanical property and the self-repairing efficiency are improved simultaneously. The quadruple HBs with high binding energy are used as strong physical crosslinking points, so that the high-strength high-shape-fixity high-strength high-binding-energy quadruple HBs have high tensile strength and good shape fixity, and single HBs with low binding energy in side chains are easy to diffuse and exchange, so that the rapid healing efficiency is realized under medium conditions. By combining and adjusting the two types of HBs, the elastomer with high toughness, puncture resistance and tear resistance is prepared.

3. Light transmission test

The polyurethane elastomers (0.7mm thick) prepared in examples 1 to 6 were measured by an ultraviolet spectrophotometer, and as a result, as shown in fig. 10, the polyurethane elastomers prepared in each example had a transmittance of 90% or more and had excellent transmittance.

Comparative example 1

Compared with the example 5, only 20mmol of solid chain extender HMIC is added in the step (2), the reaction is stirred at 250rpm for 0.5h, the addition reaction of GL is not carried out, and the rest steps are the same as the example 1.

Comparative example 2

Compared with the example 8, 10mmol of chain extender GL dissolved in 20mLN, N-Dimethylformamide (DMF) is added in the step (2), the reaction is continued for 3h under the condition of 250rpm, 10mmol of solid chain extender HMIC is added, the reaction is continued for 0.5h under the condition of 250rpm, and the rest steps are the same as the example 1.

The performance results of the polyurethane elastomers prepared in example 5 and comparative examples 1 and 2 are shown in table 1.

Table 1: mechanical properties and repair Performance data

	Example 5	Comparative example 1	Comparative example 2
				Tensile Strength (MPa)	20.5309±0.5284	58.1745±1.3951	17.2829±0.1593
Elongation at Break (%)	2043.7494±136.0977	148.3576±37.0352	1936.2992±122.0172
				Toughness (MJ/m)2)	146.093±8.2	42.692±6.722	118.373±1.545
Energy of fracture at notch (KJ/m)2)	13.798±0.184	2.374±0.271	11.892±0.396
				Repair 3h stress repair efficiency at 80 (%)	81.83±1.64	15.94±0.87	80.04±1.09
Repair efficiency at 80 ℃ for 6h stress repair (%)	93.45±1.76	39.54±1.26	90.56±2.53

As can be seen from Table 1, the polyurethane prepared by using HMIC and GL as chain extenders in a composite manner according to a specific reaction sequence has the advantages that the mechanical properties and the self-repairing efficiency are improved simultaneously through the synergy of four strong HBs in a main chain and a single weak HBs in a side chain. The stress repair efficiency reaches 81.83 percent after 3 hours at 80 ℃, 93.45 percent after 6 hours, the rapid repair is realized, and the excellent effect of remarkably improving the repair efficiency is achieved.