A polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer and its preparation method

Abstract

The present invention discloses a polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer and a preparation method thereof. A polyester-carbon dioxide-based polycarbonate-polyester copolymer with a triblock structure is obtained by initiating and catalyzing the copolymerization of an epoxide, carbon dioxide, and highly active tetrachlorophthalic anhydride through a metal catalyst or a Lewis acid-base pair. The polycarbonate segment formed by the long-chain epoxide 1 and carbon dioxide has a low glass transition temperature (T g1 < -20 °C); while the polyester segment formed by tetrachlorophthalic anhydride and the short-chain epoxide has a high glass transition temperature (T g2 ≥ 100 °C). Therefore, the triblock copolymer has two distinct glass transition temperatures, and its unique microphase separation structure endows it with the thermoplastic processability of plastics and the high elasticity of rubbers.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more specifically, to a polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer and a preparation method thereof. Background Art

[0002] Traditional transparent elastomers mainly include polyurethane elastomers, polyvinyl chloride elastomers, and silicone rubber elastomers, etc. These traditional elastomer materials are difficult to degrade, and cause serious "white pollution" after being discarded into the environment. Therefore, it is very necessary to develop biodegradable transparent elastomer materials that also have good thermal properties and mechanical properties.

[0003] The copolymer of alkylene oxide and carbon dioxide (CO2) is a transparent and completely biodegradable environmentally friendly plastic. Chinese Patent CN109485842A discloses a bio-based elastomer prepared from the copolymer of allyl glycidyl ether with flexible chains and carbon dioxide, and its glass transition temperature can reach -38.8 °C. The terminal double bond on the side chain can undergo a thiol-ene click reaction with alkyl mercaptan to generate hyperbranched side chains. Chinese Patent CN116836390A discloses a synthesis method of flexible polythioether rubber. Using 3,6-dioxa-1,8-octanedithiol, allyl glycidyl ether, and a trithiol substance, an addition reaction of epoxy and thiol, and double bond and thiol is carried out to obtain a dithiol reaction solution with side hydroxyl groups. The dithiol reaction solution is then subjected to a polyaddition reaction with 1,5-hexadiene to obtain flexible polythioether rubber, and the glass transition temperature of the synthesized flexible polythioether rubber reaches below -65 °C.

[0004] ABA triblock or multiblock copolymers with a microphase separation structure have the thermoplastic processability of plastics and the high elasticity of rubbers. In recent years, researchers have begun to focus on the design and synthesis of CO2-based TPEs, and this type of polymer is mainly composed of ABA triblock and multiblock structures. The characteristic of this type of triblock copolymer is that the middle is a soft segment with a low Tg, and both ends are rigid or hard segments with strong interactions. Chinese Patent CN118206729A discloses a tetrachlorophthalic anhydride / epoxide / carbon dioxide triblock copolymer and a preparation method thereof. The glass transition temperature of the copolymer prepared by this method can reach 100 °C. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide a polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer with two glass transition temperatures, one low and one high, high strength, high ductility and extremely high elastic recovery performance, and a preparation method thereof. The present invention first reacts alkoxides with different chain lengths with CO2, and uses a cheap, easily available, simple and efficient metal catalyst system or a non-metal Lewis acid and a single-initiator or double-initiator organic ammonium salt two-component catalyst system to catalytically prepare a softer polycarbonate containing long branches; secondly, tetrachlorophthalic anhydride and epoxide are introduced into the copolymerization system of long-chain alkoxide and CO2, and the epoxide and tetrachlorophthalic anhydride copolymerize to generate harder polyester segments at both ends of the polycarbonate, thereby preparing a triblock polyester-polycarbonate copolymer with a hard-soft-hard structure.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer, which is a tetrachlorophthalic anhydride / epoxide 1 / epoxide 2 / carbon dioxide quaternary triblock structural copolymer;

[0008] The epoxide 2 is epoxyhexane, epoxyoctane, butyl glycidyl ether, octyl glycidyl ether or allyl glycidyl ether;

[0009] When the epoxide 2 is epoxyhexane, epoxyoctane, butyl glycidyl ether or octyl glycidyl ether, tetrachlorophthalic anhydride and epoxide 1 polymerize to form a hard polyester segment, and epoxide 2 reacts with carbon dioxide to form a soft polycarbonate segment, and its structure is shown in the following formula (a);

[0010] If the epoxide 2 is allyl glycidyl ether, a polycarbonate with double bonds at the ends of the branches is generated, and under ultraviolet light irradiation conditions, the terminal double bonds further undergo a thiol-ene click reaction with thiol to obtain a grafted alkyl long chain, and its structure is shown in the following formula (b):

[0011]

[0012] Where a≥1, b≥1, and both a and b are integers.

[0013] Preferably, the epoxide 1 is ethylene oxide, propylene oxide, epichlorohydrin or epoxybutane.

[0014] Preferably, when the epoxide 2 is allyl glycidyl ether, the tetrachlorophthalic anhydride / epoxide 1 / allyl glycidyl ether / carbon dioxide quaternary triblock copolymer further undergoes a thiol-ene click reaction with n-butyl mercaptan, sec-butyl mercaptan, isobutyl mercaptan, n-pentyl mercaptan, 2-pentanethiol, isopentyl mercaptan, n-hexyl mercaptan, n-heptyl mercaptan, n-octyl mercaptan, sec-octyl mercaptan, isooctyl mercaptan, n-decyl mercaptan, n-nonyl mercaptan, tert-nonyl mercaptan, dodecyl mercaptan, tetradecyl mercaptan, hexadecyl mercaptan or n-octadecyl mercaptan to obtain a grafted alkyl long chain.

[0015] A preparation method of a polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer. The preparation method of the tetrachlorophthalic anhydride / epoxide 1 / epoxide 2 / carbon dioxide quaternary triblock copolymer includes the following two methods:

[0016] Method 1: (a) Add part of epoxide 1, epoxide 2, part of tetrachlorophthalic anhydride, and a single initiator catalyst into a high-pressure reactor under anhydrous and anaerobic conditions, introduce carbon dioxide, and stop the reaction after reacting for a period of time under magnetic stirring and heating conditions; (b) After the reaction is completed, cool the reactor; under anhydrous and anaerobic conditions, continue to add the remaining same amount of epoxide 1 and tetrachlorophthalic anhydride, and continue to react for a period of time, and then obtain a purified quaternary block copolymer through precipitation and drying; the molar ratio of the total epoxide 1 to epoxide 2 is 1:10 to 1:1; the molar ratio of epoxide 2 to the total tetrachlorophthalic anhydride is 6:1 to 2:1; the molar ratio of epoxide 2 to the single initiator catalyst is 2000:1 to 500:1;

[0017] Method 2: (a) Add epoxide 2 and a double initiator catalyst into a high-pressure reactor under anhydrous and anaerobic conditions, introduce carbon dioxide, and stop the reaction after reacting for a period of time under magnetic stirring and heating conditions; (b) After the reaction is completed, cool the reactor; under anhydrous and anaerobic conditions, add epoxide 1 and tetrachlorophthalic anhydride, and continue to react for a period of time, and then obtain a purified quaternary block copolymer through precipitation and drying; the molar ratio of epoxide 1 to epoxide 2 is 1:10 to 1:1; the molar ratio of epoxide 2 to tetrachlorophthalic anhydride is 6:1 to 2:1; the molar ratio of epoxide 2 to the double initiator catalyst is 3000:1 to 1000:1.

[0018] A preparation method of a polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer. The preparation of the tetrachlorophthalic anhydride / epoxide 1 / allyl glycidyl ether / carbon dioxide / thiol to obtain a polyester-carbon dioxide-based polycarbonate-polyester triblock copolymer includes the following steps:

[0019] (1) Add a double initiator catalyst and allyl glycidyl ether into a high-pressure reactor under anhydrous and anaerobic conditions, fill in carbon dioxide, and stop the reaction after reacting for a period of time under magnetic stirring and heating conditions;

[0020] After the reaction is completed, cool the reaction kettle to room temperature. Under anhydrous and anaerobic conditions, continue to add tetrachlorophthalic anhydride and epoxide 1. After reacting for a period of time under magnetic stirring and heating, stop the reaction. Dissolve the product in dichloromethane and precipitate and purify it in ethanol to obtain a quaternary triblock intermediate product;

[0021] After the second-step reaction is completed, dissolve the purified intermediate in dichloromethane, add alkyl mercaptan and photosensitizer 2, 2-dimethoxy-2-phenylethanone. Under ultraviolet radiation, the alkyl mercaptan reacts with the double bond to obtain a grafted alkyl long-chain triblock copolymer product;

[0022] The molar ratio of allyl glycidyl ether to the double-initiating catalyst is 3000:1 to 1000:1; the molar ratio of tetrachlorophthalic anhydride to epoxide 1 is 1:20 to 1:2; the molar ratio of tetrachlorophthalic anhydride to allyl glycidyl ether is 1000:2000 to 4000:2000; the addition amount of alkyl mercaptan is 1 - 1.2 times the number of C=C double bonds contained in the triblock copolymer, and the addition amount of the photosensitizer is 0.05 - 0.5% of the mass of the triblock copolymer.

[0023] Preferably, the single-initiating catalyst is a heterogeneous metal catalyst, a homogeneous metal catalyst or a two-component catalyst of a Lewis acid and an organic amine or an organic ammonium salt; the double-initiating catalyst is a two-component catalyst of a Lewis acid and a bisquaternary ammonium salt.

[0024] Preferably, the heterogeneous metal catalyst is a zinc compound / polyactive hydrogen compound mixed system, a rare earth metal complex and a double metal cyanide; the homogeneous metal catalyst is a metal porphyrin complex, a metal porphyrin complex, a β-diketiminate zinc catalyst or a polynuclear metal complex with a macrocyclic ligand; the Lewis acid is an organic boride.

[0025] Preferably, the single-initiating catalyst is triethylamine, tributylamine, bis(triphenylphosphonium) ammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium succinate, tetrabutylammonium terephthalate or 1,8-diazabicyclo[5.4.0]undec-7-ene; the double-initiator is tetrabutylammonium succinate, tetrabutylammonium terephthalate or tetrabutylammonium isophthalate.

[0026] Preferably, the temperature of the reaction is 50 - 70 °C, the reaction pressure is 1 - 3 MPa, and the total reaction time is 20 - 50 hours.

[0027] Preferably, in step (3), the wavelength of the ultraviolet light is 375 nm, the light intensity is 35 mw / cm 2 , the illumination time is 1 - 20 min, and the reaction temperature is room temperature.

[0028] In the polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer, the weight content of the polyester molecular chain segment is 20-80%, and the weight content of the polycarbonate molecular chain segment is 80-20%.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) In the present invention, a polyester-polycarbonate-polyester copolymer with a triblock structure is obtained by catalytically initiating the terpolymerization of epoxide 1, epoxide 2, carbon dioxide, and highly active tetrachlorophthalic anhydride. Tetrachlorophthalic anhydride is a cheap and easily available raw material with very high reactivity. By using its copolymerization reaction with epoxide, the prepared polyester chain segment has very high strength and glass transition temperature. In the present invention, an epoxide with a flexible chain is selected to copolymerize with carbon dioxide to obtain a polycarbonate chain segment with very high toughness, and this chain segment has a very low glass transition temperature. The linear polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer prepared in the present invention simultaneously has two glass transition temperatures, one high and one low (T g1 <-20 °C, T g2 ≥100 °C) and more excellent resilience, and its mechanical properties are also better than those of traditional elastomers. The polycarbonate chain segment formed by long-chain epoxide 1 and carbon dioxide has a low glass transition temperature (T g1 <-20 °C); while the polyester chain segment formed by tetrachlorophthalic anhydride and short-chain epoxide has a high glass transition temperature (T g2 ≥100 °C). Therefore, this triblock copolymer has two obvious glass transition temperatures, and its unique microphase separation structure endows it with the thermoplastic processability of plastics and the high elasticity of rubber.

[0031] (2) The polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer prepared in the present invention is non-toxic and not prone to migration or leaching. It is synthesized from carbon dioxide, which meets the goals of carbon peak and carbon neutrality, is green and environmentally friendly; it has full biodegradability and is an environmentally friendly material. Description of the Drawings

[0032] Figure 1 1H NMR spectra of the carbon dioxide-based polycarbonate and polyester-carbon dioxide-based polycarbonate-polyester triblock copolymer obtained in the first and second reaction steps of Example 3 of the present invention.

[0033] Figure 2 1H NMR spectra of the carbon dioxide-based polycarbonate, polyester-carbon dioxide-based polycarbonate-polyester, and polyester-thiol grafted carbon dioxide-based polycarbonate-polyester triblock copolymer obtained in the first, second, and third reaction steps of Example 8 of the present invention. Detailed Description of the Invention Example 1

[0034] In an anhydrous and anaerobic environment, 6.7 g of cyclohexene oxide, 43 mg of tetrabutylammonium isophthalate, and 800 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. 1.0 MPa of carbon dioxide was charged, and the reaction was carried out at 60 °C for 15 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 4.8 g of tetrachlorophthalic anhydride and 16 g of propylene oxide were added to the reactor, and the reaction was continued at 60 °C for 6 h. After the reaction was completed, the carbon dioxide pressure was released, the product was dissolved in dichloromethane, and precipitated in ethanol to obtain a triblock polymer. After vacuum drying the polymer, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. The first-step reaction: Mn1 = 54.3 kDa, PDI1 = 1.16; the conversion rate of cyclohexene oxide was 97%, and the amount of cyclic carbonate formed was 5 wt%; the second-step reaction: Mn2 = 61.8 kDa, PDI2 = 1.21; the polyester content was 29.8 wt%, and the polycarbonate content was 70.2 wt%; T g1 =-5 °C, T g2 =100 °C; the tensile strength was 19 MPa, and the elongation at break was 840%. Example 2

[0035] In an anhydrous and anaerobic environment, 8.52 g of octene oxide, 43 mg of tetrabutylammonium isophthalate, and 800 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. 1.0 MPa of carbon dioxide was charged, and the reaction was carried out at 60 °C for 25 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 4.8 g of tetrachlorophthalic anhydride and 16 g of propylene oxide were added to the reactor, and the reaction was continued at 60 °C for 6 h. After the reaction was completed, the carbon dioxide pressure was released, the product was dissolved in dichloromethane, and precipitated in ethanol to obtain a triblock polymer. After vacuum drying the polymer, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. The first-step reaction: Mn1 = 45.8 kDa, PDI1 = 1.31; the conversion rate of octene oxide was 98%, and the amount of cyclic carbonate formed was 6 wt%; the second-step reaction: Mn2 = 58.6 kDa, PDI2 = 1.36; the polyester content was 30.6 wt%, and the polycarbonate content was 69.4 wt%; T g1 =-5 °C, T g2 =100 °C; the tensile strength was 18 MPa, and the elongation at break was 880%. Example 3

[0036] In an anhydrous and anaerobic environment, 12.4 g of octyl glycidyl ether, 43 mg of tetrabutylammonium isophthalate, and 800 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. Carbon dioxide was charged at 1.0 MPa, and the reaction was carried out at 60 °C for 30 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 4.8 g of tetrachlorophthalic anhydride and 16 g of propylene oxide were added to the reactor, and the reaction was continued at 60 °C for 6 h. After the reaction was completed, the carbon dioxide pressure was released. The product was dissolved in dichloromethane and precipitated in ethanol to obtain a triblock polymer. After vacuum drying the polymer, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. First-step reaction: Mn1 = 54.9 kDa, PDI1 = 1.37; the conversion rate of octyl glycidyl ether was 95%, and the amount of cyclic carbonate formed was 6 wt%; Second-step reaction: Mn2 = 64.9 kDa, PDI2 = 1.41; the polyester content was 29.6 wt%, and the polycarbonate content was 70.4 wt%; T g1 =-31 °C, T g2 = 100 °C; the tensile strength was 18 MPa, and the elongation at break was 900%. The 1H NMR spectrum of the obtained tetrachlorophthalic anhydride / propylene oxide / octyl glycidyl ether / carbon dioxide tetrablock copolymer is as shown in Figure 1 shown. Example 4

[0037] In an anhydrous and anaerobic environment, 12.4 g of octyl glycidyl ether, 43 mg of tetrabutylammonium isophthalate, and 800 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. Carbon dioxide was charged at 1.0 MPa, and the reaction was carried out at 60 °C for 30 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 5.7 g of tetrachlorophthalic anhydride and 23 g of propylene oxide were added to the reactor, and the reaction was continued at 60 °C for 6 h. After the reaction was completed, the carbon dioxide pressure was released. The product was dissolved in dichloromethane and precipitated in ethanol to obtain a triblock polymer. After vacuum drying the polymer, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. First-step reaction: Mn1 = 54.3 kDa, PDI1 = 1.38; the conversion rate of octyl glycidyl ether was 94%, and the amount of cyclic carbonate formed was 7 wt%; Second-step reaction: Mn2 = 69.9 kDa, PDI2 = 1.40; the polyester content was 38.1 wt%, and the polycarbonate content was 61.9 wt%; T g1 =-30 °C, T g2 = 101 °C; the tensile strength was 20 MPa, and the elongation at break was 860%. Example 5

[0038] In an anhydrous and anaerobic environment, 12.4 g of octyl glycidyl ether, 43 mg of tetrabutylammonium isophthalate, and 800 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. 1.0 MPa of carbon dioxide was charged, and the reaction was carried out at 70 °C for 25 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 4.8 g of tetrachlorophthalic anhydride and 16 g of propylene oxide were added to the reactor, and the reaction was continued at 60 °C for 6 h. After the reaction was completed, the carbon dioxide pressure was released. The product was dissolved in dichloromethane and precipitated in ethanol to obtain a triblock polymer. After the polymer was dried in vacuo, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. First-step reaction: Mn1 = 49.9 kDa, PDI1 = 1.39; the conversion rate of octyl glycidyl ether was 97%, and the amount of cyclic carbonate formed was 13%; Second-step reaction: Mn2 = 63.7 kDa, PDI2 = 1.44; polyester content was 30.1%, polycarbonate content was 60.9%; T g1 =-31 °C, T g2 = 101 °C; Tensile strength was 19 MPa, and elongation at break was 870%. Example 6

[0039] In an anhydrous and anaerobic environment, 2.4 g of tetrachlorophthalic anhydride, 8 g of propylene oxide, 12.4 g of octyl glycidyl ether, 50 mg of bis(triphenylphosphine) ammonium chloride, and 90 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. 1.0 MPa of carbon dioxide was charged, and the reaction was carried out at 60 °C for 40 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 2.4 g of tetrachlorophthalic anhydride and 8 g of propylene oxide were added to the reactor, and the reaction was continued at 60 °C for 6 h. After the reaction was completed, the carbon dioxide pressure was released. The product was dissolved in dichloromethane and precipitated in ethanol to obtain a triblock polymer. After the polymer was dried in vacuo, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. First-step reaction: Mn1 = 38.5 kDa, PDI1 = 1.57; the conversion rate of octyl glycidyl ether was 97%, and the amount of cyclic carbonate formed was 18%; Second-step reaction: Mn2 = 44.8 kDa, PDI2 = 1.41; polyester content was 35.3 wt%, polycarbonate content was 64.7%; T g1 =-31 °C, T g2 = 100 °C; Tensile strength was 20 MPa, and elongation at break was 600%. Example 7

[0040] In an anhydrous and oxygen-free environment, 11.4 g of allyl glycidyl ether, 32.2 mg of tetrabutylammonium isophthalate, and 600 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. Carbon dioxide was charged at 1.5 MPa, and the reaction was carried out at 45 °C for 36 h. After the reactor was cooled, in an anhydrous and oxygen-free environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 8.6 g of tetrachlorophthalic anhydride and 29 g of propylene oxide were added to the reactor, and the reaction was continued at 50 °C for 12 h. After the reaction was completed, the carbon dioxide pressure was released, and the product was dissolved in dichloromethane and precipitated in ethanol to obtain a quaternary triblock polymer intermediate. After vacuum drying the polymer, a small amount was taken for molecular weight testing and NMR analysis. The purified quaternary triblock polymer intermediate was dissolved in dichloromethane, 1.8 g of n-octanethiol and 0.1 g of 2,2-dimethoxy-2-phenylethanone were added, and n-octanethiol reacted with the double bond under ultraviolet radiation. The reaction mixture was dropped into stirred ethanol for precipitation, and then the dissolution and precipitation were repeated three times to obtain a grafted alkyl long-chain triblock copolymer product. After vacuum drying the polymer, molecular weight testing, NMR, thermal properties, and mechanical properties were analyzed. First-step reaction: Mn1 = 61.5 kDa, PDI1 = 1.17; AGE conversion rate was 75%, and the cyclic carbonate content was 7%; Second-step reaction: Mn2 = 86.7 kDa, PDI2 = 1.23; Third-step reaction: Mn3 = 101.3 kDa, PDI3 = 1.21; Polyester content was 48.4 wt%, polycarbonate content was 34.9%, and polyether content was 16.7%; T g1 = -28 °C, T g2 = 101 °C; Tensile strength was 16 MPa, and elongation at break was 1310%. Example 8

[0041] In an anhydrous and anaerobic environment, 11.4 g of allyl glycidyl ether, 32.2 mg of tetrabutylammonium isophthalate, and 600 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. 1.5 MPa of carbon dioxide was charged, and the reaction was carried out at 45 °C for 36 h. After the reactor was cooled, in an anhydrous and anaerobic environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 8.6 g of tetrachlorophthalic anhydride and 29 g of propylene oxide were added to the reactor, and the reaction was continued at 50 °C for 12 h. After the reaction was completed, the carbon dioxide pressure was released, the product was dissolved in dichloromethane, and precipitated in ethanol to obtain a quaternary triblock polymer intermediate. After the polymer was dried in vacuo, a small amount was taken for molecular weight testing and NMR analysis. The purified quaternary triblock polymer intermediate was dissolved in dichloromethane, 2.3 g of n-butyl mercaptan and 0.1 g of 2,2-dimethoxy-2-phenylethanone were added, and n-butyl mercaptan reacted with the double bond under ultraviolet radiation. The reacted mixture was dropped into stirred ethanol for precipitation, and then the dissolution and precipitation were repeated three times to obtain a grafted alkyl long-chain triblock copolymer product. After the polymer was dried in vacuo, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. First-step reaction: Mn1 = 60.8 kDa, PDI1 = 1.14; AGE conversion rate was 73%, and the cyclic carbonate content was 8%; Second-step reaction: Mn2 = 84.9 kDa, PDI2 = 1.19; Third-step reaction: Mn3 = 95.7 kDa, PDI3 = 1.24; Polyester content was 55.4 wt%, polycarbonate content was 29.7%, and polyether content was 14.9%; T g1 = -23 °C, T g2 = 100 °C; Tensile strength was 17 MPa, and elongation at break was 1260%. The 1H NMR spectra of the allyl glycidyl ether / carbon dioxide binary copolymer, tetrachlorophthalic anhydride / propylene oxide / allyl glycidyl ether / carbon dioxide quaternary block copolymer, and grafted alkyl long-chain block copolymer product are as shown in Figure 2 shown. Example 9

[0042] In an anhydrous and oxygen-free environment, 11.4 g of allyl glycidyl ether, 32.2 mg of tetrabutylammonium isophthalate, and 600 μL of triethylboron solution were successively added to a 50 mL high-pressure reactor. Carbon dioxide was charged at 1.5 MPa, and the reaction was carried out at 45 °C for 36 h. After the reactor was cooled, in an anhydrous and oxygen-free environment, a small amount of the product was first taken out for molecular weight testing and NMR analysis. Then, 8.6 g of tetrachlorophthalic anhydride and 29 g of propylene oxide were added to the reactor, and the reaction was continued at 50 °C for 12 h. After the reaction was completed, the carbon dioxide pressure was released, and the product was dissolved in dichloromethane and precipitated in ethanol to obtain a quaternary triblock polymer intermediate. After vacuum drying the polymer, a small amount was taken for molecular weight testing and NMR analysis. The purified quaternary triblock polymer intermediate was dissolved in dichloromethane, 1.3 g of n-dodecyl mercaptan and 0.1 g of 2,2-dimethoxy-2-phenylethanone were added, and n-dodecyl mercaptan reacted with the double bond under ultraviolet radiation. The reaction mixture was dropped into stirred ethanol for precipitation, and then the dissolution and precipitation were repeated three times to obtain a grafted alkyl long-chain triblock copolymer product. After vacuum drying the polymer, molecular weight testing, NMR, thermal properties, and mechanical properties analysis were performed. The first-step reaction: Mn1 = 62.2 kDa, PDI1 = 1.16; the conversion rate of AGE was 76%, and the content of cyclic carbonate was 5%; the second-step reaction: Mn2 = 85.3 kDa, PDI2 = 1.37; the third-step reaction: Mn3 = 114.2 kDa, PDI3 = 1.26; the polyester content was 39.4 wt%, the polycarbonate content was 44.5 wt%, and the polyether content was 16.1%; T g1 = -38 °C, T g2 = 101 °C; the tensile strength was 13 MPa, and the elongation at break was 1460%.

Claims

1. A polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer, characterized in that It is a tetrachlorophthalic anhydride / epoxide 1 / epoxide 2 / carbon dioxide quaternary triblock copolymer; The epoxide 2 is epoxyhexane, epoxyoctane, butyl glycidyl ether, octyl glycidyl ether or allyl glycidyl ether; When the epoxide 2 is epoxyhexane, epoxyoctane, butyl glycidyl ether or octyl glycidyl ether, tetrachlorophthalic anhydride and epoxide 1 polymerize to form a hard polyester segment, and epoxide 2 reacts with carbon dioxide to form a soft polycarbonate segment, and its structure is shown in the following formula (a); If the epoxide 2 is allyl glycidyl ether, a polycarbonate with a double bond at the end of the branch chain is formed. Under ultraviolet light irradiation conditions, the terminal double bond further undergoes a thiol-ene click reaction with thiol to obtain a grafted alkyl long chain, and its structure is shown in the following formula (b): where a≥1, b≥1, and a and b are both integers; 。 2. A method for preparing the polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer as described in claim 1, characterized in that The preparation method of the tetrachlorophthalic anhydride / epoxide 1 / epoxide 2 / carbon dioxide quaternary triblock copolymer includes the following steps: (a) Add epoxide 2 and a double initiating catalyst into a high-pressure reactor under anhydrous and anaerobic conditions, introduce carbon dioxide, react for a period of time under magnetic stirring and heating conditions, and then stop; (b) After the reaction is completed, cool the reactor; under anhydrous and anaerobic conditions, add epoxide 1 and tetrachlorophthalic anhydride, continue to react for a period of time, and then obtain a purified quaternary triblock copolymer through precipitation and drying; the molar ratio of epoxide 1 to epoxide 2 is 1:10~1:1; the molar ratio of epoxide 2 to tetrachlorophthalic anhydride is 6:1~2:1; the molar ratio of epoxide 2 to the double initiating catalyst is 3000:1~1000:1; the double initiating catalyst is tetrabutylammonium succinate, tetrabutylammonium terephthalate or tetrabutylammonium isophthalate; The reaction temperature is 50 - 70 °C, the reaction pressure is 1 - 3 MPa, and the total reaction time is 20 - 50 hours.

3. A method for preparing the polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer as described in claim 2, characterized in that It includes the following steps: (1) Add the double initiating catalyst and allyl glycidyl ether into a high-pressure reactor under anhydrous and anaerobic conditions, fill with carbon dioxide, react for a period of time under magnetic stirring and heating conditions, and then stop; (2) After the reaction is completed, cool the reactor to room temperature. Under anhydrous and anaerobic conditions, continue to add tetrachlorophthalic anhydride and epoxide 1, react for a period of time under magnetic stirring and heating conditions, and then stop. Dissolve the product with dichloromethane and precipitate and purify it in ethanol to obtain a quaternary triblock intermediate product; (3) After the second reaction is completed, dissolve the purified intermediate in dichloromethane, add alkyl thiol and a photosensitizer 2,2-dimethoxy-2-phenylethanone, and under ultraviolet light irradiation, the alkyl thiol reacts with the double bond to obtain a grafted alkyl long chain triblock copolymer product; The molar ratio of allyl glycidyl ether to the double-initiating catalyst is 3000:1 to 1000:1; the molar ratio of tetrachlorophthalic anhydride to epoxide 1 is 1:20 to 1:2; the molar ratio of tetrachlorophthalic anhydride to allyl glycidyl ether is 1000:2000 to 4000:2000; the addition amount of alkyl mercaptan is 1 - 1.2 times the number of C=C double bonds contained in the triblock copolymer, and the addition amount of the photosensitizer is 0.05 - 0.5% of the mass of the triblock copolymer; The double-initiating catalyst described above is tetrabutylammonium succinate, tetrabutylammonium terephthalate or tetrabutylammonium isophthalate.

4. The preparation method of the polyester-carbon dioxide-based polycarbonate-polyester triblock biodegradable elastomer according to claim 3, characterized in that The wavelength of the ultraviolet light described in step (3) is 375 nm, and the light intensity is 35 mw / cm 2 , the light irradiation time is 1 - 20 min, and the reaction temperature is room temperature.

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