Elastomer and preparation method thereof

Abstract

The invention relates to the field of materials, and discloses an elastomer and a preparation method thereof.The preparation method comprises the steps that in the inert gas atmosphere and in the presence of a catalyst, an azobenzene derivative serves as an end initiator to initiate a caprolactone monomer to be subjected to a polymerization reaction, a polymer is obtained, then the polymer and functional raw materials are mixed, and the elastomer is obtained, the functional raw materials comprise one or more of tannic acid, baicalein and glycyrrhizic acid. Due to the excellent performance of the prepared elastomer, the elastomer has wide application prospects in the fields of intelligent wound dressings, degradable medical adhesives and the like.

Description

Technical Field

[0001] The present invention relates to the field of materials, and in particular to an elastomer and a preparation method thereof. Background Art

[0002] Polycaprolactone (PCL) elastomers have attracted significant attention in the fields of medicine, flexible electronics, and biodegradable packaging due to their excellent biocompatibility, biodegradability, and low-temperature toughness. Current research focuses on optimizing their properties through chemical modification and physical blending, including the following: 1. Chemical modification: (1) Block / graft copolymerization, such as copolymerization with flexible segments (such as PEG, PTMG) to reduce crystallinity and improve elasticity (such as PCL-b-PEG block copolymer). Introducing dynamic covalent bonds (such as disulfide bonds, borate bonds) to impart self-healing ability. (2) Cross-linking network design, improving mechanical strength through UV curing or thermal cross-linking (such as through acrylate end group modification), or achieving recyclability through reversible cross-linking (such as Diels-Alder reaction).

[0003] 2. Physical blending: (1) Blending with flexible polymers, such as PLA, PBAT, etc. to improve brittleness. (2) Adding nanomaterials, such as nanocellulose, montmorillonite, etc. to improve mechanical properties.

[0004] These existing chemical or physical methods still have the following problems: 1. The preparation process is complicated, with many by-products and the consumption of a large amount of solvent.

[0005] 2. Mechanical properties are difficult to effectively control and cannot meet actual application needs.

[0006] 3. Poor multifunctionality, making it difficult to combine controllable mechanical properties, self-repair, recycling and excellent biocompatibility.

[0007] 4. Processing and stability issues: Low thermal stability leads to easy oxidation during melt processing (>60°C), requiring the addition of antioxidants (such as BHT). Low melt strength leads to easy collapse during 3D printing, requiring increased melt viscosity (such as chain extension reactions). Summary of the Invention

[0008] The purpose of the present invention is to provide an elastomer and a preparation method thereof in order to overcome the problems that the existing polycaprolactone elastomer has a single function, mechanical properties that are difficult to meet requirements, or a complicated preparation process.

[0009] In order to achieve the above-mentioned objectives, the first aspect of the present invention provides an elastomer and a preparation method thereof, wherein the preparation method comprises: in an inert gas atmosphere, in the presence of a catalyst, using an azobenzene derivative as a terminal initiator to initiate a polymerization reaction of a caprolactone monomer to obtain a polymer, and then mixing the polymer with a functional raw material to obtain the elastomer, wherein the functional raw material comprises one or more of tannic acid, baicalein and glycyrrhizic acid.

[0010] The second aspect of the present invention provides an elastomer, which is prepared according to the preparation method described in the first aspect of the present invention.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. By selecting functional groups as initiators and adopting bulk polymerization, the preparation method is simple, environmentally friendly, has few by-products, and does not require the use of solvents.

[0012] 2. By introducing non-covalent bonds and combining them with optical isomerization, mechanical dynamic transformation can be achieved, thereby meeting the application needs of more smart materials.

[0013] 3. By introducing non-covalent bonds and selecting natural organic compounds as hydrogen bond donors, the elastomer is given reversible dynamic bonds, thereby giving it self-healing ability. The addition of natural medicines is beneficial to improving the biocompatibility of the elastomer. Based on the activity of natural medicines themselves, the synthetic strategy realizes the integration of the "treatment-repair" dual functions.

[0014] 4. By introducing non-covalent bonds, the elastomer is given reversible dissociation-recombination ability, thereby giving it excellent processing properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the reaction process of caprolactone monomer and azobenzene derivative; Figure 2 This is a schematic diagram of the reaction process between the polymer and glycyrrhizic acid; Figure 3 It is a schematic diagram of converting a trans-configuration (trans) polymer into a cis-configuration (cis); Figure 4 is the H NMR spectrum of the elastomer; Figure 5 is the thermogravimetric analysis diagram of the elastomer; Figure 6 This is a test diagram of the mechanical properties of the elastomer; Figure 7 This is a self-healing test diagram of the elastomer; Figure 8 This is a diagram of the in vitro biocompatibility test of elastomers. DETAILED DESCRIPTION

[0016] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0017] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] In addition, the term "and / or" in the specification and claims is used to describe an association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0020] A first aspect of the present invention provides an elastomer and a method for preparing the same, wherein the preparation method comprises: in an inert gas atmosphere, in the presence of a catalyst, using an azobenzene derivative as a terminal initiator to initiate a polymerization reaction of a caprolactone monomer to obtain a polymer, and then mixing the polymer with a functional raw material to obtain the elastomer, wherein the functional raw material comprises one or more of tannic acid, baicalein and glycyrrhizic acid.

[0021] Preferably, the molar ratio of the azobenzene derivative to the caprolactone monomer is 100-2000: 1. The molar ratio of the azobenzene derivative to the caprolactone monomer can be 100: 1, 200: 1, 300: 1, 500: 1, 800: 1, 1000: 1, 1200: 1, 1500: 1, 1700: 1, 2000: 1, or any value within a numerical range consisting of any two of these numbers.

[0022] Preferably, the mass ratio of the polymer to the functional raw material is 1-5: 1. The mass ratio of the polymer to the functional raw material can be any value within the range of 1:1, 2:1, 3:1, 4:1, 5:1, or any two of them.

[0023] Preferably, the polymerization reaction temperature is 100-200° C., and the reaction time is 24-48 hours. The reaction temperature can be 100° C., 120° C., 140° C., 150° C., 160° C., 180° C., 200° C., or any value within a numerical range consisting of any two thereof, and the reaction time can be 24 hours, 28 hours, 30 hours, 32 hours, 36 hours, 40 hours, 44 hours, 48 ​​hours, or any value within a numerical range consisting of any two thereof.

[0024] Preferably, the mixing is performed under ultrasound at a temperature of 30-40° C. for 20-40 minutes. The mixing temperature can be 30° C., 32° C., 34° C., 36° C., 38° C., 40° C., or any value within a numerical range consisting of any two thereof. The mixing time can be 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, or any value within a numerical range consisting of any two thereof. There are no particular requirements for the frequency of ultrasound, and it can be, for example, 800-1000 kHz.

[0025] Preferably, the catalyst comprises stannous octoate, and the amount of stannous octoate used per 1 mol of the caprolactone monomer is 10-100 μl. The amount of stannous octoate used per 1 mol of the caprolactone monomer can be 10 μl, 20 μl, 30 μl, 50 μl, 60 μl, 80 μl, 100 μl, or any value within a numerical range consisting of any two of these numbers.

[0026] Preferably, the preparation method further comprises inducing the elastomer to transform into an isomer with a different configuration under light exposure, wherein the light exposure wavelength is 360-420 nm and the duration is 10-30 minutes. Research has found that by controlling the light exposure wavelength to transform the prepared elastomer (cis) into an isomer with a different configuration (trans), certain properties of the elastomer can be improved (such as a large-scale shift in mechanical properties), enabling it to meet specific requirements. For example, in medical hemostatic materials, the cis configuration has a blood absorption capacity 1000 times that of the trans configuration at the same volume. Furthermore, the isomer with a different configuration (cis) can be converted back to the prepared elastomer (trans) by heating or exposure to natural light (380-780 nm).

[0027] Preferably, the light intensity is 150-200 mW / cm².

[0028] Preferably, the azobenzene derivative includes 4-n-butyl-(4'-hydroxy)azobenzene and / or 2-ethyl-(4'-hydroxy)azobenzene, and the preparation method thereof includes: A solution A comprising p-n-butylaniline and / or p-ethylaniline is first mixed with a solution B comprising sodium nitrite to obtain a solution C; Mixing the solution C with a solution D comprising phenol, sodium hydroxide, and sodium carbonate for a second time to obtain a solution E; The solution E is subjected to a third reaction to obtain the 4-n-butyl-(4'-hydroxy)azobenzene and / or 2-ethyl-(4'-hydroxy)azobenzene.

[0029] Preferably, the molar ratio of the total amount of the p-butylaniline and / or p-ethylaniline to the sodium nitrite is 1:0.5-2.

[0030] Preferably, the molar ratio of phenol, sodium hydroxide and sodium carbonate is 1:1:1.5-1.7.

[0031] Preferably, the molar ratio of the total amount of the p-n-butylaniline and / or p-ethylaniline to the phenol is 1:0.5-2.

[0032] Preferably, the third reaction is carried out in an ice-water bath for 2-5 hours.

[0033] The second aspect of the present invention provides an elastomer, which is prepared according to the preparation method described in the first aspect of the present invention.

[0034] Preferably, the number average molecular weight Mn of the elastomer is 30,000-50,000, and the weight average molecular weight Mw is 60,000-70,000.

[0035] Preferably, the polydispersity index PDI of the elastomer does not exceed 1.5.

[0036] Preferably, according to the strain-stress test in accordance with GB / T528-1998, the tensile strength of the elastomer is 14-20 MPa, and the elongation at break is 10-15%.

[0037] Preferably, when there are scratches on the surface of the elastomer, the scratch healing rate is not less than 98% when heated at 40-60° C. for 20-50 minutes.

[0038] The present invention will be further described below with reference to specific embodiments.

[0039] In the following examples and comparative examples, unless otherwise specified, all reagents and instruments used without manufacturer identification are commercially available. For examples in which specific conditions are not specified, conventional conditions or those recommended by the manufacturer were followed. Room temperature refers to 20-25°C.

[0040] Preparation Example 1 Preparation of 4-n-butyl-(4'-hydroxy)azobenzene First, 12 g (80 mmol) of p-butylaniline was dissolved in 200 mL of deionized water and 20 mL of concentrated hydrochloric acid to obtain solution A.

[0041] Dissolve 5.6 g (80 mmol) of sodium nitrite in 100 mL of deionized water to form solution B.

[0042] In an ice-water bath, slowly add solution B dropwise (complete addition within half an hour) to solution A to form solution C.

[0043] Solution D was prepared by dissolving 7.6 g (80 mmol) of phenol, 3.2 g (80 mmol) of sodium hydroxide, and 14 g (130 mmol) of sodium carbonate in 200 mL of deionized water.

[0044] Solution C was slowly added (addition completed within half an hour) to Solution D to obtain Solution E, which was then kept in an ice-water bath for 3 hours. After the reaction, the product was isolated by filtration, washed with deionized water, and finally dried under vacuum to obtain 4-n-butyl-(4'-hydroxy)azobenzene (AZ). Example 1

[0045] Preparation of elastomers (including trans and cis configurations) Caprolactone (CL) is used as monomer and Sn(Oct)2 is used as catalyst. The preparation process is as follows: Figure 1-3 The specific operations are as follows: The AZ and caprolactone (CL) monomers from Preparation Example 1 were thoroughly mixed at a molar ratio of 500:1 and placed in a dry silanized glass ampoule. 50 μl of Sn(Oct)2 was added for every 1 mol of caprolactone monomer. The ampoule was sealed after three vacuum evacuations and nitrogen replacements, and then immersed in an oil bath preheated to 150°C for 30 hours. After the reaction was completed, the product was dissolved in dichloromethane and precipitated in methanol (repeated three times). Finally, the product was dried in a vacuum oven for four days to constant weight to obtain a polymer. The reaction process is as follows: Figure 1 shown.

[0046] The polymer was mixed with glycyrrhizic acid at a mass ratio of 1.5:1 under ultrasonication at 37°C for 30 minutes. Figure 2 As shown, a trans-configuration (trans) elastomer is obtained.

[0047] Then, the elastomer with cis configuration was obtained by irradiation at 365 nm (intensity of 176 mW / cm²) for 20 min at room temperature. Figure 3 shown. Example 2

[0048] The process was carried out in the same manner as in Example 1, except that the molar ratio of AZ to CL was 1200:1, the reaction temperature was 150° C., and the mass ratio of the polymer to glycyrrhizic acid was 3:1. Example 3

[0049] The process was carried out in the same manner as in Example 1, except that the molar ratio of AZ to CL was 2000:1, the reaction temperature was 150° C., and the mass ratio of the polymer to glycyrrhizic acid was 5:1.

[0050] The prepared elastomer is subjected to multi-scale performance tests as follows.

[0051] The gel permeation chromatography (GPC) curves of the elastomers prepared in Examples 1-3 were analyzed. In the figure, P1-P3 correspond to the elastomers obtained in Examples 1-3, respectively (the Mn, Mw, and PDI of the elastomers of different configurations prepared in the same example are the same, so only the result of one of them is recorded for analysis). The results are as follows: Figure 4 As shown, the number average molecular weight Mn of the prepared elastomer is about 40,000, the weight average molecular weight Mw is more than 50,000 or more than 60,000, and the polydispersity index PDI is less than 1.5.

[0052] The chemical structures of the elastomers prepared in Examples 1-3 (the analysis results were the same for different configurations) were further characterized by H NMR spectroscopy. The test instrument was a German Bruker ARX 400 NMR spectrometer with a resonance frequency of 400 MHz, TMS as the internal standard, and deuterated chloroform (CDCl3) as the solvent. The test was carried out at room temperature. The results are as follows: Figure 4 As shown in the figure, the letters marked in the H NMR spectrum correspond to the letters a, b, c, d, and e in the polycaprolactone structural formula, corresponding to the hydrogen atoms at different positions in the elastomer. The H NMR spectrum confirms the successful synthesis of the elastomer. The absence of impurity peaks in the H NMR spectrum demonstrates the purity of the synthesized material.

[0053] Thermogravimetric analysis (TG) was performed using a German Netzsch TG209F3-ASC thermogravimetric analyzer (the sample was the trans configuration of the elastomer prepared in Example 2; the cis configuration would automatically transform to the trans configuration under the influence of high temperature and therefore could not be measured). N2 atmosphere (60 mL / min), sample mass 10 ± 2 mg, heating rate 20 ° C / min, scanning temperature range from room temperature to 800 ° C, using an empty crucible as a blank correction, and recording the enthalpy change during the heating process. The results are shown in Figure 2. Figure 5As shown in the figure, it can be seen that the thermal decomposition temperature of the elastomer is between 275-440℃, and the initial decomposition temperature is much higher than its melting point (60℃), which means that the elastomer can be processed at temperatures above the melting point without thermal decomposition, and has good thermal stability and a wide operating temperature range.

[0054] The mechanical properties of the elastomer (including trans and cis configurations) obtained in Example 2 were further tested using a universal tensile machine and a dynamic mechanical analyzer (Netzsch DMA 242E Artemis, Germany). The results are as follows: Figure 6 shown.

[0055] Figure 6 (a)-(c) are the mechanical strength of the elastomer tested by dynamic mechanical analyzer.

[0056] Figure 6 (a) Linear Viscoelasticity (LVE) test, which aims to describe the viscoelastic properties of materials under small deformations to determine Figure 6 The strain conditions of the test conditions (b) and (c) finally determined that the strain value of both the trans configuration and the cis configuration was 0.1%.

[0057] Figure 6 (b) Temperature scan of the elastomer (including trans and cis configurations) prepared in Example 2, with a fixed oscillation frequency of 1 Hz and a strain of 0.1%, observing the temperature-dependent rheological behavior of the elastomer from -15°C to 100°C. Both the storage modulus G' and loss modulus G" of the elastomer decrease with increasing temperature, and the elastomer sequentially undergoes a glassy state (<26°C), a rubbery state (26-55°C), and a viscous flow state (>55°C). The figure clearly shows that G' and G" of the cis- and trans-configurations of the elastomer tend to overlap, which is presumably related to the thermal responsiveness of the cis- and trans-configurations of the elastomer.

[0058] Figure 6 (c) shows a frequency sweep of the elastomer from Example 2 (including both trans and cis configurations), observed from 0.01 Hz to 15 Hz, at a fixed temperature of 25°C and a strain of 0.1%. This shows the frequency-dependent rheological behavior of elastomers with different configurations. The G´ and G" values ​​for the cis and trans configurations show unprecedented differences, demonstrating that the mechanical properties of elastomers can vary significantly depending on their configuration, providing a foundation for their application in smart materials and other fields.

[0059] Figure 6(d) shows the strain-stress curve of the elastomer from Example 2 tested on a universal tensile machine. Tensile testing was conducted in accordance with GB / T528-1998 using dumbbell-shaped specimens with a working area of ​​10 mm × 4 mm and a tensile rate of 250 mm / min. Three specimens were collected per group, and the results were averaged. The tensile strengths of the trans- and cis-configured elastomers are 17.05 MPa and 15.35 MPa, respectively, and their elongations at break are 12.24% and 10.32%, respectively, demonstrating excellent tensile properties. The trans-configured elastomer exhibits superior tensile properties, which is attributed to its higher hydrogen bond crosslink density. Figure 6 The overall results show that the mechanical properties of the synthesized elastomeric material are controllable, the cis- and trans-configurations can be interchanged, and it has very amazing large-span mechanical transition characteristics.

[0060] like Figure 7 As shown, using the elastomer prepared in Example 2 as the object, we observed the reconstruction dynamics of the hydrogen bond network during the material self-healing process at the nanoscale for the first time through the peak force quantitative mode of atomic force microscopy, as follows: Use a scalpel to forcefully scratch a mark on the surface of the trans-configuration elastomer. The result is as follows Figure 7 As shown in (a), Figure 7 (b) is the microscopic state of the scratch. Figure 7 (c) shows that the initial scratch depth is 5.1 μm. The trans-configured elastomer is then heated at 50 °C for 20 minutes. Figure 7 As shown in (d), the scratch healed obviously. Figure 7 (e) is the microscopic state of the scratch after healing. Figure 7 (f) The scratch depth after healing is only 67.4 nm, and the healing rate is as high as 98.7% (healing rate = 1-healed scratch depth / original scratch depth*100).

[0061] Similarly, a trace was scratched on the surface of the cis-configuration elastomer and heated at 50°C for 40 minutes. The results are as follows: Figure 7 (g) shows that the scratch healed obviously. Figure 7 (h) is the microscopic state of the healed cis-elastic body. Figure 7 (i) The scratch depth of the healed cis-elastomer is only 72 nm, and the healing rate is as high as 98.6%.

[0062] The above scratch tests demonstrate that elasticity can be dynamically repaired by heating. They also demonstrate that the trans configuration repairs faster than the cis configuration, which is related to its higher hydrogen bond crosslinking density and stronger mechanical properties. The self-healing properties of the elastomer prepared by this invention offer broad potential for applications in various fields, including medicine, environmental protection, and repair. For example, it can be used to prepare surgical sutures, sustained-release drug delivery vehicles, and tissue engineering scaffolds. These applications can not only reduce postoperative scarring and pain, but also improve patients' recovery speed and quality of life.

[0063] The elastomer prepared in Example 2 was used as the research object. The material was cut into cylindrical structures (thickness 1 mm, diameter 6 mm), disinfected with 75% ethanol overnight (24 hours), and washed with phosphate buffer. In vitro biocompatibility experiments and colony formation experiments were then performed to evaluate the effect of the obtained material on cell viability.

[0064] The specific methods of in vitro biocompatibility experiments are as follows: The cell counting kit (CCK-8) was commercially available, and human umbilical vein endothelial cells (HUVECs) were used for cell culture and purchased from the Cell Bank of the Chinese Academy of Sciences (Shanghai, China).

[0065] First, HUVEC cells were digested, centrifuged, and counted. HUVEC cells were resuspended in DMEM medium (Gibco) containing 1% penicillin-streptomycin solution (Gibco) and 10% fetal bovine serum (Gibco) at a cell density of 8 × 10 cells per ml. 5 cells.

[0066] Subsequently, the sterilized samples to be tested were placed in a 96-well plate (n = 5 replicates), and blank and negative control groups were set up according to experimental routine requirements. 1 mL of HUVEC cell suspension was inoculated into each well. The plates were incubated in a 37°C incubator with 5% carbon dioxide. On the first, second, and third days of culture, the culture medium was removed, and fresh culture medium (500 μL) containing CCK-8 solution (100 μL, 5 mg / mL) was added to each well, and incubation continued at 37°C for 4 hours.

[0067] The OD value of the solution was measured at 450 nm using a microplate reader (ThermoFisher Scientific). The cell viability (%) was calculated using the formula: (OD 实验组 -OD 空白） / (OD 对照组 -OD 空白 ) × 100% to calculate the cell viability of the two materials corresponding to the number of culture days.

[0068] To observe the proliferation morphology of cells on the samples, HUVECs were stained with Calcein AM (A017, USA) for 20 minutes after incubation for 3 days. Subsequently, the cells were gently washed three times with PBS, and the spreading and attachment of cells on the samples were observed using a confocal laser scanning microscope (Nikon Eclipse Ts2-FL, Japan).

[0069] The cell clone formation assay method is as follows: HUVEC cells in the logarithmic growth phase were centrifuged and counted. Then, they were seeded into 6-well plates at a density of 2,000 cells per well. The sample to be tested was added simultaneously and arranged crosswise to evenly disperse the cells. The plates were placed in an incubator and observed regularly. After 3-5 days, when obvious colonies (clones) were observed, the culture plates were removed and culture was terminated. The culture medium was carefully removed and the plates were thoroughly rinsed three times with PBS. The plates were then stained with Coomassie Brilliant Blue fixative at room temperature for 10 minutes. The staining solution was discarded, the plates were rinsed three times with deionized water, and dried at room temperature. An inverted phase contrast microscope (Leica DMIL-PH1, Germany) was used to observe cell colony formation.

[0070] Figure 8 (a) and Figure 8 (c) is the test of trans-configuration elastomer, Figure 8 (b) and 8 (d) are tests of cis-configuration elastomers. Figure 8 (a) and 8 (b) are the results observed under a laser confocal microscope after Calcein AM staining. It is obvious that the cells are mainly green, indicating that most of the cells are alive. Figure 8 Figures (c) and 8 (d) show the results of cell colony formation experiments, demonstrating the presence of distinct cell colonies on the outer wall of the elastomer. Laser confocal microscopy revealed that most HUVEC cells exhibited an oval structure, were able to spread more widely, and formed tighter intercellular connections, leading to cell clustering. Colony formation experiments demonstrated that the HUVEC cell line had a high survival rate and robust proliferation capacity. Figure 8 (e) shows the cytotoxicity results of the CCK-8 assay. The data demonstrate that the cell viability of the prepared elastomer remains above 85% (in compliance with ISO 10993-5 standards) over a three-day period of co-culture with cells. The cis-form elastomer exhibits superior biocompatibility (above 90%). Therefore, biocompatibility testing demonstrates that the prepared elastomer exhibits excellent cell affinity and fully meets the biocompatibility requirements for intelligent biomedical applications.

[0071] In summary, the excellent performance of the elastomer prepared by the present invention enables it to show broad application prospects in the fields of smart wound dressings, degradable medical adhesives, etc.

[0072] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention may be subjected to various simple modifications, including combining the specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing an elastomer, characterized in that: The preparation method comprises: in an inert gas atmosphere and in the presence of a catalyst, using an azobenzene derivative as a terminal initiator to initiate a polymerization reaction of a caprolactone monomer to obtain a polymer, and then mixing the polymer with a functional raw material to obtain an elastomer, wherein the functional raw material comprises one or more of tannic acid, baicalein and glycyrrhizic acid.

2. The preparation method according to claim 1, wherein The molar ratio of the azobenzene derivative to the caprolactone monomer is 100-2000:1; And / or, the mass ratio of the polymer to the functional raw material is 1-5:

1.

3. The preparation method according to claim 1 or 2, wherein The polymerization reaction temperature is 100-200°C and the time is 24-48h; And / or, the mixing is performed under ultrasound, with a mixing temperature of 30-40° C. and a mixing time of 20-40 min.

4. The preparation method according to claim 3, wherein The catalyst includes stannous octoate, and the amount of stannous octoate used per 1 mole of the caprolactone monomer is 10-100 μl.

5. The preparation method according to claim 3, wherein The preparation method further comprises: inducing the elastomer to transform into an isomer with another configuration under light irradiation, wherein the light irradiation wavelength is 360-420 nm and the time is 10-30 minutes.

6. The preparation method according to claim 4 or 5, wherein The azobenzene derivatives include 4-n-butyl-(4'-hydroxy)azobenzene and / or 2-ethyl-(4'-hydroxy)azobenzene, and the preparation method thereof includes: A solution A comprising p-n-butylaniline and / or p-ethylaniline is first mixed with a solution B comprising sodium nitrite to obtain a solution C; Mixing the solution C with a solution D comprising phenol, sodium hydroxide, and sodium carbonate for a second time to obtain a solution E; The solution E is subjected to a third reaction to obtain the 4-n-butyl-(4'-hydroxy)azobenzene and / or 2-ethyl-(4'-hydroxy)azobenzene.

7. The preparation method according to claim 6, wherein The molar ratio of the total amount of the p-butylaniline and / or p-ethylaniline to the sodium nitrite is 1:0.5-2; and / or, the molar ratio of phenol, sodium hydroxide and sodium carbonate is 1:1:1.5-2; and / or, the molar ratio of the total amount of the p-butylaniline and / or p-ethylaniline to the phenol is 1:0.5-2; And / or, the third reaction is carried out in an ice-water bath with a reaction time of 2-5 h.

8. An elastomer, characterized in that Prepared according to the preparation method according to any one of claims 1 to 7.

9. The elastic body according to claim 8, wherein The number average molecular weight Mn of the elastomer is 30,000-50,000, and the weight average molecular weight Mw is 60,000-70,000.

10. The elastic body according to claim 8 or 9, wherein The polydispersity index PDI of the elastomer does not exceed 1.5.

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