CN114380973B

CN114380973B - Self-repairing polyurethane elastomer based on bile acid molecules and preparation method thereof

Info

Publication number: CN114380973B
Application number: CN202111509816.3A
Authority: CN
Inventors: 贾永光; 王琳; 刘欢; 杨军忠; 刘卅; 林彩红
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-12-10
Filing date: 2021-12-10
Publication date: 2023-03-21
Anticipated expiration: 2041-12-10
Also published as: CN114380973A

Abstract

The invention belongs to the technical field of intravascular stent materials, and discloses a self-repairing polyurethane elastomer based on bile acid molecules and a preparation method thereof. The method comprises the following steps: 1) Reacting lithocholic acid with ethylene glycol to obtain a bile acid glycol monomer; 2) The self-repairing polyurethane elastomer is obtained by reacting a bile acid diol monomer, polyethylene glycol and hexamethylene diisocyanate under the action of a catalyst by taking an organic solvent as a reaction medium. The method of the invention is simple, and can be used for mass production, and the prepared polyurethane elastomer not only maintains the elastic performance of the elastomer, but also has better strength, and simultaneously has the performances of self-repairing, low acidic inflammation of degradation products in the material body and the like. The elastomer of the invention is used for preparing cardiovascular stents.

Description

Self-repairing polyurethane elastomer based on bile acid molecules and preparation method thereof

Technical Field

The invention belongs to the technical field of biomedical materials, and particularly relates to a bile acid molecule-based self-repairing polyurethane elastomer and a preparation method thereof.

Background

Along with the improvement of living standard, the unreasonable eating habits gradually lead to the occurrence of cardiovascular diseases, and become an important reason for death of patients worldwide. Vascular stent therapy is the most important method for treating cardiovascular stenosis. The current metal stents are prone to problems of regeneration of stenosis, thrombosis in the stent and permanent retention in the body. The advent of bio-elastomers effectively overcomes the shortcomings of metal stents.

The polymer elastomers currently available for stent materials mainly include polyesters and polyurethanes. The polyester is generally polylactic acid (PLA), polylactic-co-glycolic acid (PLGA), poly-epsilon-caprolactone (PCL), or the like. PLA and PLGA overcome the problem that metal materials are not degradable, however, the inflammation reaction caused by the acidity of the degraded products of PLA and PLGA cannot be ignored. PCL has the advantages of low immunogenicity, good thermal stability and the like, but PCL is slowly degraded and has relatively poor biocompatibility. When the existing polyurethane elastomer is used for a stent, inflammatory reaction is caused due to reasons such as incapability of degradation, biological toxicity and the like. Therefore, the preparation of the elastomer with the self-repairing function and the degradation product which does not cause local strong inflammation has important significance for developing safer in-vivo stents.

Disclosure of Invention

Aiming at the defects of the existing bracket material, the invention aims to provide a self-repairing polyurethane elastomer based on bile acid molecules and a preparation method thereof. The high-elasticity self-repairing polyurethane is prepared by using polyethylene glycol, a diol monomer derived from bile acid and diisocyanate under the action of a catalyst. The polyurethane elastomer prepared by the invention has better biocompatibility, and the degradation product is slightly acidic. The degradation products of the elastomer are polyethylene glycol with low molecular weight and bile acid molecules with high pKa, and are not easy to cause inflammatory reaction. Meanwhile, the polyurethane elastomer can obtain self-repairing polyurethane elastomers with different strengths by controlling the proportion of polyethylene glycol and bile acid diol.

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

a preparation method of a self-repairing polyurethane elastomer based on bile acid molecules comprises the following steps:

1) Reacting lithocholic acid with ethylene glycol to obtain a bile acid diol monomer (LCA-EG);

2) The method comprises the steps of taking an organic solvent as a reaction medium, and reacting a bile acid diol monomer, polyethylene glycol and hexamethylene diisocyanate under the action of a catalyst to obtain the self-repairing polyurethane elastomer (LCA-PU).

The structure of the bile acid diol monomer (LCA-EG) is

The molecular weight of the polyethylene glycol in the step 2) is 200-800, such as: PEG ₂₀₀ 、PEG ₄₀₀ 、PEG ₆₀₀ 、PEG ₈₀₀ . The molecular weight of the polyethylene glycol is preferably 200 to 600, more preferably 300 to 500.

In the step 2), the organic solvent is more than one of N, N-Dimethylformamide (DMF) and xylene. The reaction temperature is 80-100 ℃, and the reaction time is 3-8 hours; the reaction is carried out under a protective atmosphere.

In the step 2), the molar ratio of the bile acid glycol monomer, the polyethylene glycol and the hexamethylene diisocyanate is (0.7-1.3) to (2-3), preferably (0.7-1.3) to (2.5-3); the molar total amount of the bile acid diol monomer and the polyethylene glycol is 2 parts.

In the reaction in the step 1), an organic solvent is used as a reaction medium, and the organic solvent is more than one of dimethyl sulfoxide (DMSO), N-dimethylformamide, benzene, xylene and chloroform.

The reaction in the step 1) is carried out under the catalysis of a catalyst; the catalyst is an acid, such as: hydrochloric acid, sulfuric acid, p-toluenesulfonic acid; after the acid is added, the pH of the system is 2.5-3.5, preferably 3.

The molar ratio of LCA to EG in step 1) is 1 (50-100), preferably 1 (70-75).

The reaction temperature in the step 1) is 75-85 ℃, and the reaction time is 3-6 h.

After the reaction is finished, precipitating by adopting a precipitator, filtering, washing and drying.

The specific preparation steps of (LCA-EG) in the step 1) are as follows: in an organic solvent, LCA and Ethylene Glycol (EG) are mixed uniformly, then a catalyst is added for reaction, and the LCA-EG is obtained after precipitation, filtration, washing and drying.

The precipitant is 5wt% NaHCO ₃ A solution; the washing is to wash the solid with water for multiple times; the drying is vacuum drying, and the drying temperature is 30-60 ℃.

The catalyst in the step 2) is dibutyltin dilaurate or organic bismuth.

And 2) after the reaction in the step 2), pouring, drying, redissolving and forming.

The casting temperature is 80-100 ℃, and the casting time is 8-15 hours; the drying is vacuum drying, and the drying temperature is 45-55 ℃; the redissolution refers to the dissolution of the product with DMF or DMSO.

The specific preparation steps of LCA-PU are as follows: dissolving LCA-EG and PEG in an organic solvent, removing water, adding hexamethylene diisocyanate, then adding a catalyst, heating and reacting in a protective atmosphere, and obtaining the LCA-PU elastomer through pouring, drying, redissolving, forming and volatilizing.

The volatilization conditions are as follows: the temperature is 60-80 ℃, and the volatilization time is more than 50 hours.

The reaction equation for preparing LCA-EG in step 1) is as follows:

the functionalized polyurethane elastomer is obtained by the preparation method.

The self-repairing polyurethane elastomer (LCA-PU) has the structure

Reaction equation for preparing self-repairing polyurethane elastomers (LCA-PU):

the self-repairing polyurethane elastomer (LCA-PU) is used for preparing stent materials, in particular to vascular stents and cardiovascular stents.

LCA-PU is prepared by using bile acid diol monomer (LCA-EG) and hexamethylene diisocyanate as rigid chain segments, using polyethylene glycol (PEG) as flexible chain segments, utilizing the reaction combination of isocyanate and hydroxyl to generate carbamate (RNHCOOR'), and reacting under the action of a catalyst to finally obtain the polyurethane elastomer. Wherein, the strength of the polyurethane elastomer can be controlled by changing different reaction proportions of a bile acid glycol monomer (LCA-EG) of a rigid chain segment and a polyethylene glycol (PEG) of a flexible chain segment. Polyethylene glycol (PEG) can confer biocompatibility to the polymer. Then, after the bile acid polymer is degraded in vivo, the degradation product has a low acidity due to its relatively high pKa, and thus is not likely to cause an inflammatory reaction. Finally, through the interaction of hydrogen bond between carbamate groups, hydrophobic interaction between bile acid molecules and the like, an elastomer with good self-repairing function is formed.

The preparation method and the obtained product have the following advantages and beneficial effects:

(1) The invention has the advantages of cheap and easily obtained raw materials, simple synthesis method, low production cost and large-scale preparation.

(2) The synthetic product of the invention has redissolution property, can be repeatedly utilized, and can be recycled before and after the processing process.

(3) The synthetic product of the invention has self-repairing and biocompatibility, and the fractured material can be self-repaired and recover certain mechanical properties at a certain temperature.

(4) The invention successfully synthesizes the polyurethane elastomer with self-repairing and biocompatibility, can adjust the strength by controlling the proportion of soft and hard segments and the molecular weight of polyethylene glycol, has small acidity of degraded micromolecules, reduces local inflammatory reaction, and is an excellent biomedical material.

Drawings

FIG. 1 is a nuclear magnetic spectrum of a bile acid diol monomer (LCA-EG) used in example 2 and a successfully synthesized bile acid polyurethane (LCA-PU);

FIG. 2 is a stress-strain curve of LCA-PU obtained in examples 2 and 3;

FIG. 3 is the fatigue elongation curve of LCA-PU obtained in example 2;

FIG. 4 shows the results of the cytotoxicity test of LCA-PU obtained in example 2; 1mg/mL: LCA-PU addition, control: LCA-PU is not added;

FIG. 5 is a graph showing the self-healing stress-strain curve and the effects before and after healing of the LCA-PU obtained in example 2;

FIG. 6 is a graph of the results of the inflammation experiments for the LCA-PU products obtained in example 2, experimental groups: LCA-PU was used, control: blank control (without LCA-PU).

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Example 1

(1) Preparing LCA-EG: dissolving lithocholic acid (4.665g, 12.39mmol) in 24mL DMSO, adding ethylene glycol (50mL, 896 mmol), stirring uniformly, adding 500 μ L hydrochloric acid into the reaction system, wherein the pH value of the system is 3; reacting at 80 ℃ for 5 hours, and obtaining a system with 5wt% of NaHCO after the reaction ₃ Precipitating in the solution; then, filtering the precipitate to obtain a white solid, and washing the white solid for multiple times by using deionized water to obtain a purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain LCA-EG.

(2) Preparing LCA-PU: mixing LCA-EG (1 g, 2.377mmol) and PEG ₂₀₀ (475.5mg, 2.377mmol) was dissolved in 12mL of DMF, and after it was completely dissolved, it was evacuated at room temperature for 20min, at 90 ℃ for 20min, and then N ₂ Quickly adding hexamethylene diisocyanate (1070 mu L,6.6795 mmol) in the atmosphere, then adding 20 mu L of dibutyltin dilaurate catalyst, and stirring and reacting for 3 hours at 80 ℃; pouring the reactant at 80 ℃ for 12 hours, then carrying out vacuum drying at 50 ℃ for 24 hours to obtain LCA-PU, re-dissolving the LCA-PU with DMF, pouring the re-dissolved LCA-PU into a mould, and volatilizing the solvent in a 65 ℃ oven to obtain the LCA-PU film.

The tensile data and self-repair data results for the LCA-PU prepared in this example are shown in Table 1.

Example 2

(1) Preparing LCA-EG: dissolving lithocholic acid (4.665g, 12.39mmol) in 24mL DMSO, adding ethylene glycol (50mL, 896 mmol), stirring, adding 500. Mu.L hydrochloric acid into the reaction system, and reacting at 80 ℃ for 5 hours; the reacted system was at 5wt% NaHCO ₃ Precipitating in the solution; then, filtering the precipitate to obtain a white solid, and washing the white solid for multiple times by using deionized water to obtain a purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain LCA-EG.

(2) Preparing LCA-PU: LCA-EG (1 g, 2.377mmol) and PEG were added ₄₀₀ (951mg, 2.377mmol) was dissolved in 12mL of DMF, and after it was completely dissolved, it was evacuated at room temperature for 20min, at 90 ℃ for 20min, and then N was added ₂ Hexamethylene diisocyanate (1070. Mu.L, 6.6795 mmol) was added rapidly under ambient, followed by 25. Mu.L of dibutyltin dilaurate catalyst and stirred for reaction at 80 ℃ for 3 hours. Pouring the reactant at 80 ℃ for 12 hours, then vacuum-drying at 50 ℃ for 24 hours to obtain LCA-PU, re-dissolving the LCA-PU with DMF, pouring the re-dissolved LCA-PU into a mould, and volatilizing the solvent in a 65 ℃ oven to obtain the LCA-PU film.

The results of nuclear magnetic tests on LCA-EG and LCA-PU prepared in this example are shown in FIG. 1.

The LCA-PU prepared in this example was subjected to a tensile test and the results are shown in FIG. 2.

The LCA-PU prepared in this example was subjected to fatigue resistance test, and the results are shown in FIG. 3.

Dissolving LCA-PU elastomer in DMF to prepare a solution with the concentration of 1mg/mL, and dripping 9 mu L of the solution on a circular glass slide with the diameter of 8 mm; setting a blank group (i.e. control); three replicates were volatilized at 65 ℃ for 3 days, the solvent was removed, and cytotoxicity experiments were performed, and the results are shown in fig. 4.

The LCA-PU prepared in this example was subjected to a self-repairing tensile test in which a rectangular film having a length of 5cm, a width of 1cm and a thickness of 0.02cm was prepared from the LCA-PU, the film was cut from the middle, bonded together, repaired at 110 ℃ for 30 seconds, and subjected to a stress-strain tensile test, and the results are shown in FIG. 5.

The inflammation performance of the LCA-PU prepared in the example is tested, the LCA-PU is made into a film shape and covered on the incision on the back of the mouse, a blank control is arranged, and the wound section is photographed after 7 days, and the result is shown in figure 6, and the inflammatory reaction of the experimental group is less, and the repairing effect of the granulation tissue of the dermis is better than that of the control group.

Example 3

(1) Preparing LCA-EG: lithocholic acid (4.665g, 12.39mmol) was dissolved in 24mL of DMSO, and ethylene glycol (50mL, 8)96 mmol), stirring uniformly, adding 500 mu L of hydrochloric acid into the reaction system, and reacting for 5 hours at 80 ℃; the reacted system was at 5wt% NaHCO ₃ Precipitating in the solution; then, filtering the precipitate to obtain a white solid, and washing the white solid for multiple times by using deionized water to obtain a purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain LCA-EG.

(2) Preparing LCA-PU: LCA-EG (0.75g, 1.783 mmol) and PEG were added ₄₀₀ (11899mg, 2.971mmol) is dissolved in 12mL DMF, after the DMF is completely dissolved, vacuum pumping is carried out at normal temperature for 20min, vacuum pumping is carried out at 90 ℃ for 20min, and the solution is subjected to N reaction ₂ Hexamethylene diisocyanate (1070. Mu.L, 6.679 mmol) was added rapidly under ambient, followed by 25. Mu.L of dibutyltin dilaurate catalyst and stirred for reaction at 80 ℃ for 3 hours. The reactant is cast for 12 hours at the temperature of 80 ℃, and then vacuum drying is carried out for 24 hours at the temperature of 50 ℃ to obtain LCA-PU.

The results of the LCA-PU self-healing data prepared in this example are shown in Table 1.

Example 4

(2) Preparing LCA-PU: LCA-EG (1.25g, 2.971mmol) and PEG were mixed ₄₀₀ (713mg, 1.783mmol) in 12mL DMF, after it is completely dissolved, vacuum at room temperature for 20min, vacuum at 90 deg.C for 20min, N ₂ Hexamethylene diisocyanate (1070. Mu.L, 6.6795 mmol) was added rapidly under ambient, followed by 25. Mu.L of dibutyltin dilaurate catalyst and stirred for reaction at 80 ℃ for 3 hours. The reaction was cast at 80 ℃ for 12 hours and then dried under vacuum at 50 ℃ to form a gelDrying for 24 hours to obtain LCA-PU.

The LCA-PU tensile data and self-healing data results for the examples are shown in Table 1.

Example 5

(1) Preparing LCA-EG: dissolving lithocholic acid (4.665g, 12.39mmol) in 24mL DMSO, adding ethylene glycol (50mL, 896 mmol), stirring, adding 500. Mu.L hydrochloric acid into the reaction system, and reacting at 80 ℃ for 5 hours; the reacted system was at 5wt% NaHCO ₃ Precipitating in the solution; then, filtering the precipitate to obtain a white solid, and washing the white solid with deionized water for multiple times to obtain a purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain LCA-EG.

(2) Preparing LCA-PU: mixing LCA-EG (1 g, 2.377mmol) and PEG ₈₀₀ (1902mg, 2.377mmol) in 15mL DMF, after complete dissolution, vacuum at room temperature for 20min, vacuum at 90 deg.C for 20min, N ₂ Hexamethylene diisocyanate (1070. Mu.L, 6.6795 mmol) was added rapidly under ambient, followed by 30. Mu.L of dibutyltin dilaurate catalyst, and the reaction was stirred at 80 ℃ for 3 hours. The reactant is cast for 12 hours at the temperature of 80 ℃, and then vacuum drying is carried out for 24 hours at the temperature of 50 ℃ to obtain LCA-PU.

The LCA-PU tensile data and self-healing data results prepared in this example are shown in Table 1.

Comparative example 1

A preparation method of a bile acid molecule-based polyurethane elastomer comprises the following steps:

(2) Preparing LCA-PU: mixing LCA-EG (1 g, 2.377mmol) and PEG ₂₀₀₀ (4755mg, 2.377mmol) in 15mL DMF, after it was completely dissolved, vacuum at room temperature for 20min, vacuum at 90 deg.C for 20min, N ₂ Hexamethylene diisocyanate (1070. Mu.L, 6.6795 mmol) was added rapidly under ambient, followed by 55. Mu.L of dibutyltin dilaurate catalyst and stirred for reaction at 80 ℃ for 3 hours. The reactant is cast for 12 hours at the temperature of 80 ℃, and then vacuum drying is carried out for 24 hours at the temperature of 50 ℃ to obtain LCA-PU.

The results of the tensile data and the self-healing data for the LCA-PU prepared in this comparative example are shown in Table 1.

Comparative example 2

(1) Preparing CA-EG: dissolving cholic acid (12g, 29mmol) in ethylene glycol (120mL, 2150mmol), stirring to dissolve, adding 1mL hydrochloric acid into the reaction system, and reacting at 80 ℃ for 2 hours; the reacted system was at 5wt% NaHCO ₃ Precipitating in the solution; then, filtering the precipitate to obtain a white solid, and washing the white solid with deionized water for multiple times to obtain a purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain CA-EG.

(2) Preparing CA-PU: mixing CA-EG (1g, 2.209mmol) and PEG ₂₀₀ (442mg, 2.209mmol) was dissolved in 12mL of DMF, and after it was completely dissolved, it was evacuated at room temperature for 20min, at 90 ℃ for 20min, under N ₂ Hexamethylene diisocyanate (991. Mu.L, 6.1852 mmol) was added rapidly under ambient, followed by 20. Mu.L dibutyltin dilaurate catalyst, and the reaction was stirred at 80 ℃ for 3 hours. And pouring the reactant at 80 ℃ for 12 hours, then carrying out vacuum drying at 50 ℃ for 24 hours to obtain CA-PU, redissolving the CA-PU by using DMF, pouring the CA-PU into a mould, and volatilizing the solvent in a 65 ℃ oven to obtain the CA-PU film.

The tensile data and self-repair data results for the CA-PU prepared in this comparative example are shown in Table 1.

Comparative example 3

(1) Preparation of CA-EG: dissolving cholic acid (12g, 29mmol) in ethylene glycol (120mL, 2150mmol), stirring to dissolve, adding 1mL hydrochloric acid into the reaction system, and reacting at 80 ℃ for 2 hours; the reacted system was at 5wt% NaHCO ₃ Precipitating in the solution; subsequently, the precipitate was filtered to obtain a white colorWashing the solid white with deionized water for several times to obtain purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain CA-EG.

(2) Preparing CA-PU: mixing CA-EG (1g, 2.209mmol) and PEG ₄₀₀ (884mg, 2.209mmol) is dissolved in 12mL DMF, and after the DMF is completely dissolved, the mixture is vacuumized for 20min at normal temperature and vacuumized for 20min at 90 ℃ under the condition of N ₂ Hexamethylene diisocyanate (991. Mu.L, 6.1852 mmol) was added rapidly under ambient, followed by 23. Mu.L of dibutyltin dilaurate catalyst and stirred for reaction at 80 ℃ for 3 hours. And pouring the reactant at 80 ℃ for 12 hours, then carrying out vacuum drying at 50 ℃ for 24 hours to obtain CA-PU, re-dissolving the CA-PU with DMF, pouring the re-dissolved CA-PU into a mould, and volatilizing the solvent in a 65 ℃ drying oven to obtain the CA-PU film.

Comparative example 4

(1) Preparing CA-EG: dissolving cholic acid (12g, 29mmol) in ethylene glycol (120mL, 2150mmol), stirring to dissolve, adding 1mL hydrochloric acid into the reaction system, and reacting at 80 ℃ for 2 hours; the reacted system was at 5wt% NaHCO ₃ Precipitating in the solution; then, filtering the precipitate to obtain a white solid, and washing the white solid for multiple times by using deionized water to obtain a purified product; finally, the product was dried under vacuum at 50 ℃ for 24 hours to obtain CA-EG.

(2) Preparing CA-PU: mixing CA-EG (1g, 2.209mmol) and PEG ₈₀₀ (1768mg, 2.209mmol) was dissolved in 12mL of DMF, and after complete dissolution, vacuum was applied at room temperature for 20min, at 90 ℃ for 20min, and then N was applied ₂ Hexamethylene diisocyanate (991. Mu.L, 6.1852 mmol) was added rapidly under ambient, followed by 30. Mu.L of dibutyltin dilaurate catalyst and stirred for reaction at 80 ℃ for 3 hours. And pouring the reactant at 80 ℃ for 12 hours, then carrying out vacuum drying at 50 ℃ for 24 hours to obtain CA-PU, redissolving the CA-PU by using DMF, pouring the CA-PU into a mould, and volatilizing the solvent in a 65 ℃ oven to obtain the CA-PU film.

TABLE 1 data of the Performance test of the polyurethane elastomers prepared in examples 1 to 5 and comparative examples 1 to 4

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A preparation method of a self-repairing polyurethane elastomer based on bile acid molecules is characterized by comprising the following steps: the method comprises the following steps:

1) Reacting lithocholic acid with ethylene glycol to obtain a bile acid glycol monomer;

2) Reacting a bile acid diol monomer, polyethylene glycol and hexamethylene diisocyanate under the action of a catalyst by taking an organic solvent as a reaction medium to obtain a self-repairing polyurethane elastomer;

the structure of the bile acid diol monomer is

The molecular weight of the polyethylene glycol in the step 2) is 200 to 800;

the molar ratio of the bile acid glycol monomer, the polyethylene glycol and the hexamethylene diisocyanate in the step 2) (0.7-1.3): 2~3);

the concrete preparation steps of the bile acid diol monomer in the step 1) are as follows: in an organic solvent, lithocholic acid and ethylene glycol are mixed uniformly, then a catalyst is added for reaction, and a bile acid diol monomer is obtained through precipitation, filtration, washing and drying.

2. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 1, wherein the preparation method comprises the following steps: the molecular weight of the polyethylene glycol is 200 to 600;

the molar ratio of the bile acid glycol monomer, the polyethylene glycol and the hexamethylene diisocyanate in the step 2) is (0.7-1.3): 2.5-3);

the reaction temperature in the step 2) is 80 to 100 ℃, and the reaction time is 3~8 hours.

3. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 1, wherein the preparation method comprises the following steps: the molecular weight of the polyethylene glycol is 300 to 500;

the molar total amount of the bile acid diol monomer and the polyethylene glycol is 2 parts.

4. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 1, wherein the preparation method comprises the following steps: in the step 2), the organic solvent is more than one of N, N-dimethylformamide and xylene; the reaction is carried out in a protective atmosphere;

the catalyst in the step 2) is dibutyltin dilaurate or organic bismuth;

in the reaction in the step 1), an organic solvent is used as a reaction medium;

the reaction in the step 1) is carried out under the catalysis of a catalyst;

in the step 1), the molar ratio of lithocholic acid to ethylene glycol is 1 (50-100);

the reaction temperature in the step 1) is 75-85 ℃, and the reaction time is 3-6 h;

after the reaction in the step 1), precipitating by using a precipitator, filtering, washing and drying.

5. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 4, wherein the preparation method comprises the following steps: the organic solvent in the step 1) is more than one of dimethyl sulfoxide, N-dimethylformamide, benzene, xylene and chloroform;

the catalyst in the step 1) is acid, and after the acid is added, the pH value of the system is 2.5 to 3.5;

the molar ratio of lithocholic acid to ethylene glycol in the step 1) is 1 (70-75).

6. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 4, wherein the preparation method comprises the following steps:

7. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 1, wherein the preparation method comprises the following steps: after the reaction in the step 2), casting, drying, redissolving and forming;

the casting temperature is 80-100 ℃, and the casting time is 8-15 hours; the drying is vacuum drying, and the drying temperature is 45 to 55 ℃; the redissolution refers to the dissolution of the product with DMF or DMSO.

8. The preparation method of the bile acid molecule-based self-repairing polyurethane elastomer as claimed in claim 1, wherein the preparation method comprises the following steps: the self-repairing polyurethane elastomer is prepared by the following specific steps: dissolving a bile acid diol monomer and polyethylene glycol in an organic solvent, removing water, adding hexamethylene diisocyanate, then adding a catalyst, heating to react in a protective atmosphere, and obtaining the LCA-PU elastomer through pouring, drying, redissolving, molding and volatilizing.

9. A self-repairing polyurethane elastomer based on bile acid molecules obtained by the preparation method of any one of claims 1~8.

10. The use of the bile acid molecule based self-healing polyurethane elastomer of claim 9 in vascular stents.