Compounds, methods of making and using the same, homopolymers, methods of making and degrading the same

Abstract

This invention provides a compound and its preparation method, application, homopolymer and its preparation method, and degradation method, belonging to the field of polymer material synthesis technology. The compound has a structure as shown in formula (I) or formula (II): Formula (I), Formula (II). The polyester material synthesized from the compound of this invention can be used as a replacement for plastics, and can be completely degraded after use, thereby reducing the waste of fossil resources and reducing environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of polymer material synthesis technology, and in particular to a compound and its preparation method, application, homopolymer and its preparation method, and degradation method. Background Technology

[0002] Polymer materials play an important role in daily life due to their unique properties. Compared with other traditional materials, plastics have many advantages, such as durability, low density, corrosion resistance, ease of processing, and low production cost. These advantages make plastics an indispensable part of life and have a wide range of applications.

[0003] Currently, the most produced plastic components include polymers such as polyolefins. The synthesis of these polymers relies on petroleum-based monomers, requiring the consumption of significant amounts of fossil resources. Furthermore, these polymers have long degradation cycles, with most plastics taking hundreds to thousands of years to degrade. The widespread use of plastics leads to the accumulation of waste plastics in the environment, causing serious pollution.

[0004] Therefore, there is an urgent need to provide a method that can reduce the waste of fossil resources while reducing environmental pollution. Summary of the Invention

[0005] In view of the above, in order to at least partially solve at least one of the aforementioned technical problems, the present invention provides a compound and its preparation method, application, homopolymer and its preparation method, and degradation method.

[0006] According to one aspect of the present invention, a compound is provided having a structure as shown in formula (I) or formula (II):

[0007] Formula (I), Equation (II).

[0008] According to another aspect of the present invention, a method for preparing the compound as described above is provided, wherein the method for preparing the compound of formula (I) comprises: reacting 3,4-epoxy-1-butene with thiosalicylic acid in a first solvent to obtain a solution containing 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid; reacting 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in the first solvent under the catalysis of a first catalyst to obtain an esterified product; reacting the esterified product with a thioating agent to obtain a compound having the structure shown in formula (I); or, the method for preparing the compound of formula (II) comprises: reacting 3-isochromone with a thioating agent in a second solvent to obtain a compound having the structure shown in formula (II).

[0009] In some embodiments, the ring-opening reaction is carried out at a temperature of 55-65°C for 18-22 hours; the esterification reaction is carried out at a temperature of 10-30°C for 10-12 hours; the first catalyst is 4-dimethylaminopyridine; the sulfiding agent includes at least one of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiaphosphazene-2,4-disulfide and phosphorus pentasulfide; the thiolation reaction is carried out at a temperature of 110-120°C for 6-12 hours.

[0010] In some embodiments, the molar ratio of 3,4-epoxy-1-butene to thiosalicylic acid is 1:(1.05~1.1), and the molar ratio of 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 4-dimethylaminopyridine is 1:(1.4~1.6):0.2.

[0011] According to another aspect of the present invention, an application of the above-described compound as a monomer for the preparation of homopolymers is provided.

[0012] According to another aspect of the present invention, a homopolymer is provided comprising repeating units having the form shown in formula (III) or formula (IV).

[0013] Formula (III) Formula (IV).

[0014] In some embodiments, the homopolymer containing repeating units as shown in formula (III) has a molecular weight of 10,000 to 20,000 and a molecular weight distribution of 1.4 to 1.5; the homopolymer containing repeating units as shown in formula (IV) has a molecular weight of 25,000 to 30,000 and a molecular weight distribution of 1.4 to 1.5.

[0015] According to another aspect of the present invention, a method for preparing the homopolymer as described above is provided, comprising: performing ring-opening polymerization of the compound represented by formula (I) in a first solvent under the action of an initiator to prepare a homopolymer having repeating units represented by formula (III); and performing ring-opening polymerization of the compound represented by formula (II) in a first solvent under the action of an initiator to prepare a homopolymer having repeating units represented by formula (IV).

[0016] Formula (I), Equation (II).

[0017] In some embodiments, the initiator includes a cationic initiator, preferably BF3·Et2O or (Et3O).+ B(C6F5)4 – [Ph3C] + [B(C6F5)4] – Any one of the following; more preferably, the initiator is [Ph3C]. + [B(C6F5)4] – .

[0018] According to another aspect of the present invention, a method for degrading the above-described homopolymer is provided, wherein the homopolymer is degraded in an organic solvent under the catalytic action of a second catalyst.

[0019] In some embodiments, the second catalyst is 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0020] In some implementations, the degradation rate of the homopolymer is 98-100%.

[0021] According to embodiments of the present invention, a rigid benzene ring and a thiocarbonyl lactone polycyclic ring are introduced onto the compound shown in formula (I) or formula (II). The benzene ring can increase the mechanical properties of the subsequently formed homopolymer, and the thiocarbonyl lactone polycyclic ring has moderate ring strain, making it easier to undergo ring-opening polymerization, which is beneficial for the subsequent preparation of polyester compounds, thus serving as commonly used plastic substitutes and reducing the waste of fossil resources. Furthermore, it can be degraded by changing the reaction conditions, thereby reducing the environmental pollution caused by residual waste plastic products. In addition, by introducing vinyl groups onto the side chains of the compound shown in formula (I), it is helpful to further adjust the mechanical and thermodynamic properties of the polyester compounds through group modification after the homopolymer is formed, which is beneficial for further broadening the application fields of polyester compounds. Attached Figure Description

[0022] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0023] Figure 1 The hydrogen nuclear magnetic resonance spectrum of compound M1 in Example 1 of the present invention is shown;

[0024] Figure 2 The hydrogen nuclear magnetic resonance spectrum of the homopolymer PM1 of Example 1 of the present invention is shown.

[0025] Figure 3 The gel permeation chromatogram of homopolymer PM1 of Example 1 of the present invention is shown;

[0026] Figure 4 The 1H NMR spectrum of the depolymerization product DP1 of Example 1 of the present invention is shown.

[0027] Figure 5 The proton NMR spectrum of compound M2 in Example 2 of this invention is shown.

[0028] Figure 6 The 1H NMR spectrum of the homopolymer PM2 of Example 2 of the present invention is shown.

[0029] Figure 7 The gel permeation chromatogram of the homopolymer PM2 of Example 2 of the present invention is shown;

[0030] Figure 8 The nuclear magnetic resonance hydrogen spectrum of the depolymerization product DP2 of Example 2 of the present invention is shown. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0033] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0034] In this invention, the term "thiocarbonyl lactone" can be understood as a thiocarbonyl lactone, that is, the oxygen on the carbonyl group of the lactone is replaced by sulfur.

[0035] In this invention, the term "cationic polymerization" can be understood as a polymerization reaction that uses cations as active centers, and the initiator used is an electrophilic reagent that can accept electron pairs to form a cation center.

[0036] The plastic products commonly used in related technologies are mostly composed of polymers such as polyolefins. While these polymers possess high durability, they are also difficult to degrade, with most polymers taking hundreds or even thousands of years to degrade. Coupled with the massive use of plastics, this has led to a large accumulation of waste plastics in the environment. Addressing the problem of waste plastic accumulation requires not only sorting and recycling waste plastics but also reducing unnecessary plastic use to a certain extent. Furthermore, the recycling efficiency of most waste plastics is low, and the performance of the recycled products is reduced. Therefore, achieving plastic sustainability is crucial to solving the problem of plastic pollution.

[0037] In an effort to reduce reliance on fossil resources and mitigate plastic pollution, related technologies have attempted to utilize renewable energy sources as raw materials, but the subsequent recycling process remains a challenge. While developing biodegradable polymers can alleviate environmental pollution from accumulated waste plastics to some extent, these polymers typically undergo partial degradation, leaving residual polymers that still pose significant environmental pollution risks.

[0038] Related technologies have attempted to use polylactic acid (PLA) as a substitute for plastics. However, the degradation process of PLA suffers from selective depolymerization. Thermal degradation of PLA produces a mixture of various products, while tin-catalyzed chemical degradation yields stereoisomers and cyclic oligomers of lactide. Therefore, the recycling and reuse of PLA materials requires extensive separation and purification processes, hindering process simplification. Regarding the critical temperature T... c Polymers with lower polymerization and depolymerization temperatures, where the polymerization and depolymerization reactions reach equilibrium (ΔGp = 0), are prone to degradation under mild conditions. As a result, they often lack sufficient physical and mechanical properties in use. For example, fully recyclable polymers synthesized by the chemoselective synthesis of the biological derivative methylene butyl lactone not only require low-temperature synthesis, but the resulting polymers are also amorphous materials under normal conditions, resulting in poor material performance.

[0039] In realizing the concept of this invention, it was discovered that by designing specific benzothiocarbonyl lactone polycyclic compounds, the benzene ring provides the mechanical properties for subsequent plastic formation. The thiocarbonyl lactone polycyclic ring has suitable ring strain and is easy to undergo polymerization reaction through ring opening, thereby preparing polyester compounds, which can then be applied in the field of plastics, reducing dependence on fossil resources, facilitating subsequent degradation, and reducing the pollution of the environment by waste plastic products.

[0040] Specifically, according to one aspect of the present invention, a compound is provided having a structure as shown in formula (I) or formula (II):

[0041] Formula (I), Equation (II).

[0042] According to embodiments of the present invention, the compound shown in formula (I) provides a seven-membered ring of benzothiocarbonyl lactone. The seven-membered ring has greater ring strain than the six-membered ring, making it easier to undergo ring-opening polymerization to prepare thiopolyester compounds. Introducing a rigid benzene ring into the main chain enhances the mechanical properties of the polymer. Introducing vinyl groups into the side chains of the seven-membered thiocarbonyl lactone allows for post-polymerization modification. Modifying specific groups on the polymer side chains allows for adjustment of the polymer's thermal and mechanical properties, thereby broadening the polymer's functional applications. The compound shown in formula (II) provides a six-membered benzothiocarbonyl ring. Similar to formula (I), the benzene ring provides corresponding mechanical properties, enabling the preparation of thiopolyester compounds. The compounds of the present invention readily undergo ring-opening polymerization to form thiopolyester compounds, which can serve as commonly used plastic substitutes, reducing dependence on fossil resources. Furthermore, subsequent degradation under modified conditions reduces the environmental pollution caused by residual waste plastic products.

[0043] According to another aspect of the present invention, a method for preparing the compound as described above is provided, wherein the method for preparing the compound of formula (I) comprises: reacting 3,4-epoxy-1-butene with thiosalicylic acid in a first solvent to obtain a solution containing 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid; reacting 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in the first solvent under the catalysis of a first catalyst to obtain an esterified product; and reacting the esterified product with a thioating agent to obtain a compound having the structure shown in formula (I).

[0044] As can be understood, its preparation process is as follows:

[0045] .

[0046] In some embodiments, the first solvent is dichloromethane.

[0047] The method for preparing the compound shown in formula (II) includes: reacting 3-isochromone with a sulfidating agent in a second solvent to obtain a compound having the structure shown in formula (II).

[0048] As can be understood, its preparation process is as follows:

[0049] .

[0050] In some embodiments, the second solvent is toluene.

[0051] In some embodiments, the ring-opening reaction temperature is 55-65°C, for example, 55°C, 60°C, or 65°C, preferably 60°C. The reaction time is 18-22 hours, for example, 18 hours, 20 hours, or 22 hours, preferably 20 hours. The esterification reaction temperature is 10-30°C, for example, 10°C, 15°C, 20°C, 25°C, or 30°C, and the esterification reaction can be carried out at room temperature. The reaction time is 10-12 hours, for example, 10 hours, 11 hours, or 12 hours. This setting helps to promote the reaction and increase the yield of the reaction product. The first catalyst is 4-dimethylaminopyridine, which has strong nucleophilicity and accelerates the esterification reaction. In the preparation of the two compounds mentioned above, the sulfiding agent includes at least one of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphonobutane-2,4-disulfide (Lawson's reagent) and phosphorus pentasulfide. Lawson's reagent undergoes homolytic cleavage of P=S at high temperatures, generating sulfur free radicals, which then thiocarbonylate the carbonyl group of the lactone. The sulfidation mechanism of phosphorus pentasulfide is similar to that of Lawson's reagent. The conditions for the thiolation reaction are: a temperature of 110-120°C, for example, 115°C, 116°C, or 117°C (the temperature should be higher than 110°C), preferably 115°C, for 6-12 hours, for example, 6 hours, 8 hours, 10 hours, or 12 hours, preferably 6 hours.

[0052] In some embodiments, the molar ratio of 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 4-dimethylaminopyridine is 1:(1.4~1.6):0.2, for example, it can be 1:1.4:0.2, 1:1.5:0.2 or 1:1.6:0.2, preferably 1:1.5:0.2. This setting helps to promote and accelerate the smooth progress of the esterification reaction and improve the yield of the esterification product.

[0053] According to another aspect of the present invention, an application of the above-described compound as a monomer for the preparation of homopolymers is provided.

[0054] According to another aspect of the present invention, a homopolymer is provided comprising repeating units having the form shown in formula (III) or formula (IV).

[0055] Formula (III) Formula (IV).

[0056] According to embodiments of the present invention, the above-mentioned homopolymer has thiopolyester groups, giving it properties similar to plastics and good application performance, which helps to reduce dependence on fossil resources. It should be noted that post-polymerization modification with alkenyl groups is possible; specific functional groups can be added to the side chains of the homopolymer as needed, thereby broadening the application functions of the homopolymer.

[0057] In some embodiments, the molecular weight of the homopolymer containing the repeating unit shown in formula (III) is 10,000 to 20,000, for example, 10,000, 15,000 or 20,000, and the molecular weight distribution is 1.4 to 1.5, for example, 1.4, 1.45 or 1.5; the molecular weight of the homopolymer containing the repeating unit shown in formula (IV) is 25,000 to 30,000, for example, 25,000, 28,000 or 30,000, and the molecular weight distribution is 1.4 to 1.5, for example, 1.4, 1.45 or 1.5.

[0058] According to embodiments of the present invention, the aforementioned molecular weight and narrow molecular weight distribution indicate good controllability of the polymerization.

[0059] According to another aspect of the present invention, a method for preparing the homopolymer as described above is provided, comprising: performing ring-opening polymerization of the compound represented by formula (I) in a first solvent under the action of an initiator to prepare a homopolymer having repeating units represented by formula (III); and performing ring-opening polymerization of the compound represented by formula (II) in a first solvent under the action of an initiator to prepare a homopolymer having repeating units represented by formula (IV).

[0060] Formula (I), Equation (II).

[0061] The reaction process for preparing homopolymers having repeating units as shown in Formula (III) from the compound represented by Formula (I) is as follows:

[0062] The value of n ranges from 100 to 500, for example, it can be 100, 200, 300, 400 or 500.

[0063] The reaction process for preparing homopolymers having repeating units as shown in Formula (IV) from the compound represented by Formula (II) is as follows:

[0064] The value of m ranges from 100 to 500, for example, it can be 100, 200, 300, 400 or 500.

[0065] According to an embodiment of the present invention, the polymerization reaction is initiated by an initiator, which causes the two compounds to form homopolymers. The resulting homopolymers have thiopolyester groups. Due to their similarity to polyester groups, they can be applied in the field of plastics, which is beneficial for the subsequent preparation of environmentally friendly materials.

[0066] In some embodiments, the initiator includes a cationic initiator that generates a cationic active center through decomposition. This active center attacks the ester bond of the thiocarbonyl lactone monomer, causing ring-opening and homopolymerization. Preferably, the initiator is BF3·Et2O or (Et3O). + B(C6F5)4 – [Ph3C] + [B(C6F5)4] – Any one of them, more preferably [Ph3C]. + [B(C6F5)4] – .

[0067] It should be noted that [Ph3C] + [B(C6F5)4] – It is a cationic initiator that acts as an active center to react with nucleophilic sites in compounds, initiating chain polymerization and facilitating the preparation of homopolymers. [Ph3C] is used in... + [B(C6F5)4] – The polymerization reaction must be carried out in a glove box because cationic polymerization is easily interfered with by oxygen and water. As mentioned earlier, the first solvent is dichloromethane.

[0068] Preferably, the concentration of the compound during the polymerization reaction is 2 mol / L.

[0069] According to another aspect of the present invention, a method for degrading the above-described homopolymer is provided, wherein the homopolymer is degraded in an organic solvent under the catalytic action of a second catalyst.

[0070] According to an embodiment of the present invention, by adding a second catalyst, the thioester bonds in the homopolymer are activated, thereby causing the homopolymer to degrade.

[0071] In some embodiments, the second catalyst is 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

[0072] According to embodiments of the present invention, TBD has strong alkalinity, which can activate the thioester bonds in the homopolymer, reduce the energy required for their breakage, and thus promote degradation.

[0073] Preferably, the molar percentage of TBD added is 5% of the homopolymer.

[0074] The degradation process of the homopolymer having the repeating unit shown in formula (III) is as follows:

[0075] .

[0076] The degradation process of the homopolymer having the repeating unit shown in formula (IV) is as follows:

[0077] .

[0078] In some embodiments, the degradation temperature of the homopolymer having the repeating unit shown in formula (III) is 90~100°C, for example, 90°C, 100°C, preferably 100°C, and the time is 1h.

[0079] In some embodiments, the degradation temperature of the homopolymer having the repeating unit shown in formula (IV) is at room temperature for 1 hour.

[0080] It should be noted that whether heating is required in the degradation method of homopolymers depends on the stability of the sulfide ester bonds in the homopolymer backbone.

[0081] In some embodiments, the degradation rate of the homopolymer is 100%. Through the above degradation method, the homopolymer can be completely degraded, further reducing the pollution of the environment caused by the waste plastics produced from it.

[0082] In some embodiments, the organic solvent is toluene.

[0083] In some embodiments, the homopolymer having the repeating unit shown in formula (III) is degraded to obtain the compound shown in formula (V); the homopolymer having the repeating unit shown in formula (IV) is degraded to obtain the compound shown in formula (VI).

[0084] Formula (V) Formula (VI).

[0085] It should be noted that the chain growth process of this invention is based on the mechanism of cationic ring-opening polymerization, and the resulting homopolymer can be depolymerized through a back-biting reaction or a cyclization reaction. The compounds of this invention are reactive to electrophilic reagents and can undergo cationic polymerization. Furthermore, the compounds undergo sulfoxy isomerization during ring-opening polymerization, resulting in changes to the polymer backbone. After polymerization, the compounds yield homopolymers with cleavable thioester bonds in their main chain, which can be completely degraded into another small molecule compound, reducing environmental pollution.

[0086] The present invention will be further illustrated below through embodiments and related test experiments and results. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0087] It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this invention is not limited thereto. The chemicals and raw materials used in the following embodiments are all commercially available or prepared using recognized processing methods.

[0088] Example 1:

[0089] Preparation of compound M1:

[0090] 3,4-epoxy-1-butene (1.5 g, 21.4 mmol, 1 eq) was added to a dichloromethane (50 mL) solution of thiosalicylic acid (1.5 g, 22.4 mmol, 1.05 eq). The reaction solution was heated under reflux at 60 °C for 20 h, and the reaction solution gradually changed from a suspension to a pale yellow homogeneous solution.

[0091] Subsequently, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) (6.15 g, 32 mmol, 1.5 eq), 4-dimethylaminopyridine (DMAP) (0.52 g, 4.3 mmol, 0.2 eq), and 20 mL of dichloromethane were added to the above pale yellow homogeneous solution, and the reaction was allowed to proceed overnight at room temperature. Most of the solvent in the reaction solution was then removed by rotary evaporation, and the product was purified by silica gel column chromatography using an ethyl acetate / petroleum ether (EA / PE) mixture as the eluent (EA:PE = 1:3, v:v) to obtain a pale pink liquid product in 30% yield.

[0092] The pale pink liquid product (600 mg, 2.91 mmol, 1 eq) from the previous step was sulfided with Lawson's reagent. Lawson's reagent (707 mg, 1.75 mmol, 0.6 eq) was added to a toluene solution (40 mL) of the pale pink liquid product from the previous step. The solution was heated under reflux at 115 °C for 6 h, and the reaction solution gradually turned orange. The reaction solution was then cooled to room temperature, and most of the solvent was removed under reduced pressure. Using an EA / PE mixed solvent as the eluent (EA:PE = 1:8, v:v), the compound M1 was purified by silica gel column chromatography to obtain an orange-yellow liquid. The reaction equation is shown below, with a yield of 21%. Figure 1 The hydrogen nuclear magnetic resonance spectrum of compound M1 from Example 1 of this invention is shown. Figure 1 As shown, the preparation of compound M1 was verified.

[0093] .

[0094] Preparation of homopolymer PM1:

[0095] 111 mg of compound M1 and 25 μL of [Ph3C] were added. + [B(C6F5)4] – A 0.2 mol / L dichloromethane solution was added to a 4 mL reaction flask, and the stirring speed was set to 500 r / min. The reaction was carried out at room temperature for 24 h, and the polymerization reaction was conducted in a glove box. After the polymerization reaction was completed, the reaction flask was removed from the glove box, and 100 μL of a dichloromethane (DCM) solution of methanol (MeOH) (MeOH:DCM = 1:100) was added to quench the reaction. The quenched reaction solution was then precipitated into 20 mL of cold methanol and centrifuged (5000 rpm, 5 min) to remove the precipitant. The precipitate was then dissolved in 1 mL of DCM. The above precipitation process was repeated three times to ensure the removal of residual catalyst or unreacted compounds. The reaction equation is shown below. The prepared homopolymer PM1 was dried to constant weight in a vacuum drying oven at 40 °C. Figure 2 The hydrogen nuclear magnetic resonance spectrum of the homopolymer PM1 from Example 1 of this invention is shown. Figure 2 As shown, the preparation of homopolymer PM1 was confirmed, with a conversion rate of 99%. Figure 3 A gel permeation chromatogram of the homopolymer PM1 from Example 1 of the present invention is shown. Figure 3 As shown, when the ratio of compound M1 to initiator is 100:1, the molecular weight M of the resulting homopolymer PM1 is... n The value is 12700, and the molecular weight distribution M is... w / M n It is 1.47.

[0096] .

[0097] The depolymerization process of homopolymer PM1:

[0098] The depolymerization reaction of homopolymer PM1 was carried out in a glove box. 100 mg of homopolymer PM1 was added to a 4 mL reaction flask, and 1 mL of toluene was added to dissolve it, obtaining a toluene solution of homopolymer PM1. Then, 22 μL of a 1 mol / L dichloromethane solution of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was added to the reaction flask. The mixture was heated to 100 °C and reacted for 1 h with a stirring speed of 500 r / min. The reaction equation is shown below, and the depolymerization rate was 100%. Figure 4 The nuclear magnetic resonance hydrogen spectrum of the depolymerization product DP1 of Example 1 of the present invention is shown, confirming the preparation of the depolymerization product DP1.

[0099] .

[0100] Example 2:

[0101] Preparation of compound M2:

[0102] 3-Isochromone (20.0 g, 135 mmol, 1 eq) was sulfidated with Lawson's reagent. Lawson's reagent (32.8 g, 81 mmol, 0.6 eq) was added to a toluene solution (300 mL) of 3-isochromone. The solution was heated under reflux at 115 °C for 6 h, and the reaction solution gradually changed from yellow to orange. The reaction solution was then cooled to room temperature, filtered to remove insoluble impurities, and most of the solvent in the filtrate was removed under reduced pressure. Using an EA / PE mixed solvent as the eluent (EA:PE = 1:4, v:v), the solution was purified by silica gel column chromatography to obtain an orange-yellow liquid compound M2. The reaction equation is shown below, with a yield of 26%. Figure 5 The proton NMR spectrum of compound M2 from Example 2 of this invention is shown below. Figure 5 As shown, the preparation of compound M2 was verified.

[0103] .

[0104] Preparation of homopolymer PM2:

[0105] 80 mg of compound M2 and 24 μL of [Ph3C] were added. + [B(C6F5)4] – A 0.2 mol / L dichloromethane solution was added to a 4 mL reaction flask, and the stirring speed was set to 500 rpm. The mixture was stirred at room temperature for 0.5 h, and the polymerization reaction was carried out in a glove box. After the polymerization reaction was completed, the reaction flask was removed from the glove box, and 100 μL of a dichloromethane solution in methanol (MeOH:DCM = 1:100) was added to quench the reaction. The quenched reaction solution was then precipitated into 20 mL of cold methanol and centrifuged (5000 rpm, 5 min) to remove the precipitant. The precipitant was then dissolved in 1 mL of DCM. The above precipitation process was repeated three times to ensure the removal of residual catalyst or unreacted compounds. The reaction equation is shown below. The prepared homopolymer PM2 was dried to constant weight in a vacuum drying oven at 40 °C. Figure 6 The 1H NMR spectrum of the homopolymer PM2 of Example 2 of the present invention is shown, as follows: Figure 2 As shown, the preparation of homopolymer PM2 was confirmed, with an M2 conversion rate of 99%. Figure 7 The gel permeation chromatogram of the homopolymer PM2 of Example 2 of the present invention is shown. Figure 7 As shown, when the ratio of compound M2 to initiator is 100:1, the molecular weight M of the resulting homopolymer PM2 is... n The value is 26100, and the molecular weight distribution M is...w / M n It is 1.43.

[0106] .

[0107] The depolymerization process of homopolymer PM2 (biodegradable polyester material):

[0108] The depolymerization reaction of homopolymer PM2 was carried out in a glove box. 100 mg of homopolymer PM2 was added to a 4 mL reaction flask, and 1 mL of toluene was added to dissolve it, obtaining a toluene solution of homopolymer PM2. Then, 5 μL of a 1 mol / L dichloromethane solution of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was added to the reaction flask. The reaction was carried out at room temperature for 10 min. The degradation rate was relatively fast. The reaction equation is shown below, and the depolymerization rate was 100%. Figure 8 The nuclear magnetic resonance hydrogen spectrum of the depolymerization product DP2 of Example 2 of the present invention is shown, confirming the preparation of the depolymerization product DP2.

[0109] .

[0110] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a homopolymer, comprising: The compound shown in formula (I) was subjected to ring-opening polymerization in a first solvent under the action of an initiator to prepare a homopolymer having repeating units shown in formula (III); in, Formula (I); Formula (III); the initiator is [Ph3C]. + [B(C6F5)4] – ; The homopolymer has a molecular weight distribution of 1.4 to 1.5 and a molecular weight of 10,000 to 20,000.

2. The method according to claim 1, wherein, The method for preparing the compound shown in formula (I) includes: In a first solvent, 3,4-epoxy-1-butene is subjected to a ring-opening reaction with thiosalicylic acid to obtain a solution containing 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid; In a first solvent, 2-((1-hydroxybut-3-en-2-yl)thio)benzoic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were subjected to an esterification reaction under the catalysis of a first catalyst to obtain the esterified product. The esterified product was subjected to a thiolation reaction with a sulfiding agent to obtain a compound having the structure shown in formula (I).

3. The method according to claim 2, wherein, The ring-opening reaction is carried out at a temperature of 55-65°C for 18-22 hours. The esterification reaction is carried out at a temperature of 10~30℃ for 10~12h, and the first catalyst is 4-dimethylaminopyridine. The vulcanizing agent is selected from at least one of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphonium heterocyclobutane-2,4-disulfide and phosphorus pentasulfide; The conditions for the thiolation reaction are: at a temperature of 110~120℃, for 6~12 hours.

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