Process for the preparation of polythioester amides and depolymerization method thereof
By employing a two-component catalytic system for the ring-opening polymerization and depolymerization of thiazine dione monomers, the challenge of controlling the molecular weight of polythioester amides was solved, enabling the preparation of polymers with narrow molecular weights and degradability, thereby improving the recycling efficiency of the materials.
Patent Information
- Application Number
- CN202310630575.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-31
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2043-05-31
AI Technical Summary
Existing technologies make it difficult to precisely control the chemical composition and molecular weight of polythioester amides, resulting in products with low molecular weight, wide molecular weight distribution, unstable performance, and numerous byproducts, making it difficult to achieve material recycling.
A two-component catalytic system, including a co-catalyst of thiourea and an organic base, was used to prepare a polythioester amide polymer with a narrow molecular weight distribution through the ring-opening polymerization of thiazide dione monomer. The polymer was then depolymerized under anhydrous and oxygen-free conditions by adding an organic base catalyst to recover the thiazide dione monomer.
The preparation of polythioester amide polymers with narrow molecular weight distribution was achieved, with a monomer recovery rate of 50%. The materials are biodegradable, have recycling potential, and the polymer products have stable properties.
Smart Images
Figure CN116640308B_ABST
Abstract
Description
Technical Field
[0001] This disclosure belongs to the field of organic polymer materials technology, specifically relating to a method for preparing polythioesteramide and its depolymerization method. Background Technology
[0002] Polyesteramide (PEA) materials contain both ester and amide bonds, possessing both the biodegradability and compatibility of lipid compounds and retaining the excellent mechanical properties of amide compounds. Among them, poly(thioester-amide)s (PTEAs) have wide applications in polymer materials, biomaterials, membrane materials and other fields due to their excellent mechanical properties, biocompatibility, refractive index and other properties.
[0003] Polythioesteramides are variants of polyesteramides. The thioester bonds in their polymer backbone are weaker than ester bonds, making them more prone to degradation under normal conditions. Furthermore, the synthesis and recycling of polythioesteramide monomers are easier. Their preparation often involves replacing the carbon-oxygen bonds in lactone amide monomers with carbon-sulfur bonds, followed by ionic ring-opening polymerization of the lactone amide monomer to obtain polythioesteramides. Alternatively, polythioesteramides can be prepared through stepwise polymerization by replacing hydroxyl groups with thiols.
[0004] However, in related technologies, it is often difficult to precisely control the chemical composition and molecular weight of polythioester amides. The resulting polythioester amide products have low molecular weight, wide molecular weight distribution, numerous polymerization byproducts, and unstable properties. Therefore, developing a method for the preparation and depolymerization of polythioester amides with controllable polymerization behavior and material properties is of positive significance for both scientific research and industrial development. Summary of the Invention
[0005] In view of this, to solve at least one technical problem mentioned above and in other aspects of the related art, this disclosure proposes a method for preparing polythioester amide and a method for depolymerizing it. By using a two-component catalytic system to avoid thioester exchange side reactions, a depolymerizable polythioester amide polymer with a narrow molecular weight distribution can be prepared, thereby achieving the recycling of materials.
[0006] In one aspect of this disclosure, a method for preparing polythioesteramide is disclosed, comprising: adding a cocatalyst and an initiator containing thiourea and an organic base to a thiazide dione monomer solution to cause the thiazide dione monomer to undergo a ring-opening polymerization reaction to obtain a polythioesteramide polymer.
[0007] According to embodiments of this disclosure, the concentration range of the thiazine dione monomer solution includes 1.5 mol / L to 2.5 mol / L; the molar ratio of thiazine dione monomer, cocatalyst and initiator is 100:1:1.
[0008] According to embodiments of this disclosure, the polymerization reaction temperature is 25–30°C.
[0009] According to embodiments of this disclosure, the thiazine dione monomer is selected from one of the following structural formulas:
[0010] .
[0011] According to embodiments of this disclosure, the initiator includes benzyl mercaptan;
[0012] The thiourea has the following structural formula, wherein R1 and R2 are substituted or unsubstituted six-membered cycloalkanes or benzene rings.
[0013] ;
[0014] The organic base includes one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and organophosphononitrile bases; the solvent includes one of N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, chloroform, and acetonitrile.
[0015] According to embodiments of this disclosure, the acidity coefficient of the organic base is greater than 10.
[0016] According to embodiments of this disclosure, the difference in acidity coefficient between thiourea and organic base is less than 5.0.
[0017] According to embodiments of this disclosure, the method for preparing polythioesteramide further includes adding a precipitant after the polymerization reaction to precipitate the polythioesteramide polymer, wherein the precipitant includes diethyl ether.
[0018] In another aspect of this disclosure, a method for depolymerizing polythioester amides is disclosed, comprising:
[0019] The polysulfate amide prepared by the above method is dissolved in a solvent, an organic base catalyst is added, and the polysulfate amide is depolymerized and the thiamethoxam monomer is recovered under anhydrous and oxygen-free conditions.
[0020] According to the embodiments of this disclosure, the concentration of the polysulfate amide solution is not higher than 0.05 mol / L, the feeding ratio of polysulfate amide to organic base is 100:1, and the reaction time is 10 min.
[0021] According to embodiments of this disclosure, on the one hand, a two-component catalyst system comprising thiourea and an organic base is designed to regulate the polymerization behavior of the thiazine dione monomer, causing the highly nucleophilic thioanion at the end of the growing chain of the thiazine dione monomer to be converted into a more stable reactive thiourea anion, thus avoiding thioester exchange side reactions; on the other hand, by adjusting the polymerization reaction conditions, a polythioester amide polymer with a narrow molecular weight distribution is prepared. This method can utilize thiazine dione monomers with diverse structures and has a simple catalyst system design. The polymerization product is biodegradable and recyclable, showing potential application value in the preparation of novel biodegradable materials.
[0022] According to embodiments of this disclosure, the above-described preparation method involves a chemical reaction equilibrium in which polymerization and depolymerization occur in both directions. Therefore, by reducing the concentration of the polysulfate amide obtained by the aforementioned preparation method in the reaction system and adding an organic base catalyst, a depolymerization reaction, which is the reverse of the polymerization reaction, can be carried out at room temperature to quickly obtain a monomer recovery rate of approximately 50%, thereby achieving the recycling of the monomer. Attached Figure Description
[0023] Figure 1 This is a schematic diagram illustrating the preparation principle of polysulfate amide in this disclosure;
[0024] Figure 2 This is a hydrogen nuclear magnetic resonance spectrum of a polysulfide amide synthesized according to an embodiment of this disclosure;
[0025] Figure 3 This is a hydrogen nuclear magnetic resonance spectrum of a polysulfate amide synthesized according to another embodiment of this disclosure;
[0026] Figure 4 This is a hydrogen nuclear magnetic resonance spectrum of a polysulfate amide synthesized according to another embodiment of this disclosure;
[0027] Figure 5 This is a gel permeation chromatogram of a polythioester amide synthesized according to an embodiment of this disclosure;
[0028] Figure 6 This is a comparison of the proton NMR spectra of the depolymerization product of polysulfide amide and the thiazide dione monomer according to an embodiment of this disclosure. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.
[0030] The endpoints and any values of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values should be understood to include values close to such ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this disclosure.
[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0032] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.
[0033] It should be noted that, unless otherwise defined, the technical or scientific terms used in this disclosure should have the ordinary meaning understood by a person with ordinary skill in the art to which this disclosure pertains. Where the terms "first," "second," etc., are used throughout, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data described by "first," "second," etc., can be interchanged where appropriate.
[0034] In related technologies, the method for preparing polythioesteramides via anionic ring-opening polymerization often involves the sulfide anion at the end of the monomer chain nucleophilically attacking the carbonyl group on the reactant monomer, causing the carbon-sulfur bond on the monomer to break and generating a new sulfide anion active growth center. This process is repeated until a high molecular weight polythioesteramide polymer is finally produced. However, because the sulfide anion has high nucleophilicity, it attacks the carbonyl group on the already generated polymer chain, leading to severe transesterification and thus affecting the properties of the polythioesteramide polymer.
[0035] Figure 1 This is a schematic diagram illustrating the preparation principle of polysulfate amide in this disclosure.
[0036] In this disclosure, an organic base / thiourea bimolecular co-catalytic system was designed, such as Figure 1 As shown, thiourea is used to convert the thiourea anion at the end of the growing chain into a thiourea anion, thereby avoiding the thioester exchange side reaction. Under the combined action of a base catalyst with an acidity constant adapted to the polymerization constant and the thiourea anion, polymerization is further initiated, thus controlling the overall polymerization behavior.
[0037] In one aspect of this disclosure, a method for preparing polythioesteramide is disclosed, comprising: adding a cocatalyst and an initiator containing thiourea and an organic base to a thiazide dione monomer solution to cause the thiazide dione monomer to undergo a ring-opening polymerization reaction to obtain a polythioesteramide polymer.
[0038] According to embodiments of this disclosure, on the one hand, a two-component catalyst system comprising thiourea and an organic base is designed to regulate the polymerization behavior of thiazide dione monomers. The co-catalyst converts the thiourea anion at the end of the growing chain formed during the polymerization process into a thiourea anion, thereby transforming the highly nucleophilic thiourea anion at the end of the growing chain into a more stable reactive thiourea anion and avoiding thioester exchange side reactions. On the other hand, by adjusting the polymerization reaction conditions, a polythioester amide polymer with a narrow molecular weight distribution is prepared. This method can utilize thiazide dione monomers with diverse structures, has a simple catalyst system design, and the polymerization product is degradable and recyclable, showing potential application value in the preparation of novel biodegradable materials.
[0039] According to embodiments of this disclosure, the concentration range of the thiazine dione monomer solution includes 1.5 mol / L to 2.5 mol / L, for example, 1.5 mol / L, 1.7 mol / L, 1.95 mol / L, 2 mol / L, 2.1 mol / L, 2.25 mol / L, 2.3 mol / L, 2.5 mol / L; the molar ratio of thiazine dione monomer, co-catalyst and initiator is 100:1:1.
[0040] According to embodiments of this disclosure, the inventors have verified through extensive experiments that at this dosage, the co-catalyst can effectively ensure that the polymerization of thiazine dione monomers is catalyzed while avoiding thioester exchange side reactions, thereby obtaining a polythioester amide polymer with a narrow molecular weight distribution. Specifically, the polythioester amide polymer obtained in this disclosure has a number-average molecular weight range of 4000–8000 and a molecular weight distribution not exceeding 1.13.
[0041] According to embodiments of this disclosure, the polymerization reaction temperature is 25–30°C, for example, 25°C, 26.5°C, 27°C, 28°C, or 30°C.
[0042] According to the embodiments of this disclosure, the inventors have verified through numerous experiments that the polymerization behavior of thiazide dione monomers can be effectively controlled at this temperature to obtain polythioester amide polymers with narrow molecular weight distribution.
[0043] According to embodiments of this disclosure, the thiazine dione monomer is selected from one of the following structural formulas:
[0044] .
[0045] According to embodiments of this disclosure, the initiator includes benzyl mercaptan;
[0046] The thiourea has the following structural formula, wherein R1 and R2 are substituted or unsubstituted six-membered cycloalkanes or benzene rings.
[0047] ;
[0048] When there are substituents on the six-membered cycloalkane or benzene ring, the substituents can be selected from one or more combinations of halogens, C1~C10 alkyl groups, and C6~C30 aryl groups.
[0049] Organic bases include one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and organophosphononitrile bases;
[0050] The solvent includes one of N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, chloroform, and acetonitrile.
[0051] According to the embodiments of this disclosure, a highly polar organic solvent is selected to ensure the solubility of the thiazide dione monomer.
[0052] According to embodiments of this disclosure, in the polymerization of thiazine dione monomers, the role of the organic base catalyst is to activate the ends of the growing chains, increase the nucleophilicity of sulfur atoms, and improve monomer conversion. When using an organic base as a single catalyst, while activating the ends of the growing chains and promoting the polymerization reaction, the organic base catalyst also leads to thioester exchange side reactions. After introducing a thiourea catalyst, through hydrogen bonding, the thiourea catalyst itself becomes a thiourea anion, preventing the excessively nucleophilic sulfur anions from attacking the ester groups on the polymer chain, thereby causing the thioester exchange side reaction. The role of the thiourea catalyst is to reduce the nucleophilicity of sulfur atoms while activating the thiazine dione monomer to compensate for the disadvantage of decreased monomer conversion caused by reduced nucleophilicity.
[0053] According to embodiments of this disclosure, the acidity coefficient of the organic base is greater than 10.
[0054] According to embodiments of this disclosure, the difference in acidity coefficient between thiourea and organic base is less than 5.0.
[0055] According to embodiments of this disclosure, before designing a method for synthesizing polythioester amide, it is necessary to first determine the structure of the thiazide dione monomer and the organic base catalyst to be used. The thiourea catalyst is selected based on the acidity coefficient (pKa) of the organic base catalyst to ensure the matching and stability of the co-catalyst.
[0056] According to embodiments of this disclosure, the method for preparing polythioesteramide further includes adding a precipitant after the polymerization reaction to precipitate the polythioesteramide polymer, wherein the precipitant includes diethyl ether.
[0057] In another aspect of this disclosure, a method for depolymerizing polythioester amides is disclosed, comprising:
[0058] The polysulfate amide prepared by the method described above is dissolved in a solvent, an organic base catalyst is added, and the polysulfate amide is depolymerized and the thiamethoxam monomer is recovered under anhydrous and oxygen-free conditions.
[0059] According to embodiments of this disclosure, the aforementioned preparation method involves a chemical reaction equilibrium in which polymerization and depolymerization occur in both directions. Therefore, by reducing the concentration of the polysulfate amide obtained by the aforementioned preparation method in the reaction system and adding an organic base catalyst, a depolymerization reaction that is the reverse of the polymerization reaction can be carried out at room temperature to quickly obtain a monomer recovery rate of approximately 50%, thereby achieving the recycling of the monomer.
[0060] According to the embodiments of this disclosure, the concentration of the polysulfate amide solution is not higher than 0.05 mol / L, the feeding ratio of polysulfate amide to organic base is 100:1, and the reaction time is 10 min.
[0061] According to embodiments of this disclosure, the organic base catalyst used in depolymerization is the same organic base catalyst used in the preparation of polysulfide amides to facilitate the smooth progress of depolymerization.
[0062] It should be noted that the described embodiments are merely some, not all, of the embodiments disclosed herein. Other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are all within the scope of protection of this disclosure.
[0063] Example 1: Polymerization Experiment
[0064] S1: Cyclic 6-benzyl-1,4-thiazine-2,5-dione was prepared by a two-step coupling reaction using Boc-L-phenylalanine N-hydroxy ester and mercaptoacetic acid as raw materials, and the 6-benzyl-1,4-thiazine-2,5-dione was purified.
[0065] S2: 221.3 mg (1 mmol) of purified 6-benzyl-1,4-thiazine-2,5-dione (A1) was dissolved as a thiazine-dione monomer in 0.2 mL of N,N-dimethylformamide (DMF). After the thiazine-dione monomer was completely dissolved, the initiator and co-catalyst were added sequentially to initiate the polymerization reaction. The initiator for the polymerization reaction was a toluene solution of benzyl thiol (1 mmol, 0.01 mL), and the co-catalyst was 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, pKa). DMSO =13.9) toluene solution (1 mmol, 0.01 mL) and 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexylthiourea (TU, pKa)DMSO =13.2) DMF solution (1 mmol, 0.01 mL).
[0066] S3: After the reaction solution from step S2 has been allowed to stand in a glove box for 4 hours, it is removed and filtered using diethyl ether as a precipitant to obtain a polysulfate amide polymer precipitate. The polysulfate amide polymer is purified by repeated precipitation at least three times and then dried overnight in a vacuum drying oven at 40°C to obtain the polysulfate amide polymer.
[0067]
[0068] Test Example 1
[0069] A small amount of the original solution of the polythioester amide polymer prepared in Example 1 was dissolved in CDCl3. The specific structure of the polymer was characterized by nuclear magnetic resonance (NMR) and the molecular weight characteristics of the polythioester amide polymer prepared in Example 1 were analyzed by gel permeation chromatography (GPC).
[0070] Figure 2 This is the 1H NMR spectrum of the polythioester amide synthesized in Example 1 of this disclosure.
[0071] like Figure 2 As shown, a polythioesteramide polymer was successfully synthesized in Example 1. The characteristic structures of the polythioesteramide polymer are labeled 1, 2, 3, 4, and 5, and their characteristic peaks are observed in their 1H NMR spectra, indicating that the polythioesteramide polymer was successfully synthesized. Meanwhile, in... Figure 2 In the 1H NMR spectrum, x and y represent solvent impurity peaks. The absence of other impurity peaks indicates the synthesis of a relatively pure and singular polythioester amide polymer, suggesting that almost no side reactions occurred. Based on the different chemical shifts of some proton characteristic peaks between the polymer and the monomer, the monomer conversion rate of thiazine dione was calculated to be approximately 73% through integration.
[0072] Take 5 mg of the dried polythioester amide from Example 1 and determine its molecular weight using DMF-phase GPC.
[0073] Figure 5 This is a gel permeation chromatogram of a polythioester amide synthesized according to an embodiment of this disclosure.
[0074] like Figure 5 As shown, the polythioester amide prepared in Example 1 has a molecular weight of 8200 and a molecular weight distribution of 1.13.
[0075] Example 2 Polymerization Experiment +
[0076] S1: Cyclic 3,6-dimethyl-1,4-thiazine-2,5-dione was prepared by a two-step coupling reaction using tert-butoxycarbonyl-L-alanine N-succinimide ester and thiolactic acid as raw materials, and the 3,6-dimethyl-1,4-thiazine-2,5-dione was purified.
[0077] S2: 159.2 mg (1 mmol) of purified 3,6-dimethyl-1,4-thiazine-2,5-dione was dissolved in 0.2 mL of N,N-dimethylformamide (DMF). After the monomer was completely dissolved, a toluene solution of benzyl thiol (1 mmol, 0.01 mL) was added sequentially as an initiator, followed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, pKa). DMSO =13.9) toluene solution (1 mmol, 0.01 mL), 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexylthiourea (TU, pKa) DMSO Polymerization was carried out in a DMF solution (1 mmol, 0.01 mL) with a concentration of 13.2 g / L. After the solution was allowed to stand in a glove box for 4 hours, it was removed and filtered using diethyl ether as a precipitant to obtain a polysulfamide polymer precipitate. The polysulfamide polymer was purified by repeated precipitation at least three times and dried overnight in a vacuum drying oven at 40°C to obtain the final polymer product.
[0078]
[0079] Test Example 2
[0080] A small amount of the original solution of the polythioester amide polymer prepared in Example 2 was dissolved in CDCl3. The specific structure of the polymer was characterized by nuclear magnetic resonance (NMR) and the molecular weight characteristics of the polythioester amide polymer prepared in Example 2 were analyzed by gel permeation chromatography (GPC).
[0081] Figure 3 This is the 1H NMR spectrum of the polythioester amide synthesized in Example 2 of this disclosure.
[0082] like Figure 3 As shown, a polythioesteramide polymer was successfully synthesized in Example 2. The characteristic structures of the polythioesteramide polymer are labeled 1, 2, 3, and 4, and their characteristic peaks are observed in the 1H NMR spectrum, indicating that the polythioesteramide polymer was successfully synthesized. Meanwhile, in... Figure 3The 1H NMR spectrum shown contains no impurity peaks other than the solvent peak, indicating the synthesis of a relatively pure and monotypic polythioester amide polymer, suggesting that almost no side reactions occurred. Based on the different chemical shifts of some proton characteristic peaks of the polymer and monomer, the monomer conversion of thiazine dione was calculated to be approximately 32% through integration.
[0083] Example 3 Polymerization Experiment
[0084] S1: Cyclic 3-methyl-6-benzyl-1,4-thiazine-2,5-dione was prepared by a two-step coupling reaction using Boc-L-phenylalanine N-hydroxy ester and thiolactic acid as raw materials, and the 3-methyl-6-benzyl-1,4-thiazine-2,5-dione was purified.
[0085] S2: 234.3 mg (1 mmol) of purified 3-methyl-6-benzyl-1,4-thiazine-2,5-dione was dissolved in 0.2 mL of N,N-dimethylformamide (DMF). After the monomer was completely dissolved, a toluene solution of benzyl thiol (1 mmol, 0.01 mL) was added sequentially as an initiator, followed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, pKa). DMSO =13.9) toluene solution (1 mmol, 0.01 mL), 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexylthiourea (TU, pKa) DMSO Polymerization was carried out in a DMF solution (1 mmol, 0.01 mL) with a concentration of 13.2 g / L. After the solution was allowed to stand in a glove box for 4 hours, it was removed and filtered using diethyl ether as a precipitant to obtain a polysulfamide polymer precipitate. The polysulfamide polymer was purified by repeated precipitation at least three times and dried overnight in a vacuum drying oven at 40°C to obtain the final polymer product.
[0086]
[0087] Test Example 3
[0088] A small amount of the original solution of the polythioester amide polymer prepared in Example 3 was dissolved in CDCl3. The specific structure of the polymer was characterized by nuclear magnetic resonance (NMR) and the molecular weight characteristics of the polythioester amide polymer prepared in Example 3 were analyzed by gel permeation chromatography (GPC).
[0089] Figure 4 This is the 1H NMR spectrum of the polysulfide amide synthesized in Example 3 of this disclosure.
[0090] like Figure 4As shown, a polythioesteramide polymer was successfully synthesized in Example 3. The characteristic structures of the polythioesteramide polymer are labeled a and b, and the characteristic structures of the monomers are labeled A and B. Their characteristic peaks were observed in the 1H NMR spectrum, indicating that the polythioesteramide polymer was successfully prepared, and that monomers were still present in the reaction solution. Meanwhile, in Figure 4 The proton NMR spectrum shown contains no impurity peaks other than the solvent peak, indicating the synthesis of a relatively pure and monotypic polythioester amide polymer, suggesting that almost no side reactions occurred. Based on the different chemical shifts of some proton characteristic peaks of the polymer and monomer, the monomer conversion of thiamethoxam was calculated to be approximately 46% through integration.
[0091] Example 4 Depolymerization Experiment
[0092] In a glove box, the polythioesteramide polymer prepared in Example 1 was dissolved in DMF to ensure a polythioesteramide concentration of 0.05 mol / L. Triethanolamine (TEA) was added as an organic base catalyst to carry out the polymer-catalyzed depolymerization reaction. After reacting for 10 minutes, a portion of the reaction solution was dissolved in CDCl3 solvent, and the structure was analyzed using nuclear magnetic resonance (NMR) technology. The structural formula of the polythioesteramide depolymerization product (thiazindione) prepared in Example 4 is formula (A), and the structural formula of the polythioesteramide polymer prepared in Example 1 is formula (B).
[0093] Formula (A), Formula (B);
[0094] Figure 6 This is a comparison of the proton NMR spectra of the depolymerization product of polysulfide amide and the thiazide dione monomer according to an embodiment of this disclosure.
[0095] like Figure 6 As shown, the polythioesteramide polymer prepared in Example 1 and the depolymerization product of the polythioesteramide prepared in Example 4 exhibit corresponding characteristic peak structures. The characteristic structure of the polythioesteramide polymer is labeled A, and the characteristic structure of the thiazine dione monomer is labeled a. The depolymerization product of the polythioesteramide prepared in Example 4 contains both characteristic peaks A and a, indicating that the depolymerization reaction is incomplete. Based on the different chemical shifts of some proton characteristic peaks of the polymer and monomer, the conversion rate (i.e., monomer recovery rate) of the polythioesteramide polymer depolymerization reaction was calculated to be 47% through integration.
[0096] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.
Claims
1. A method for preparing a polythioesteramide, comprising: A co-catalyst and initiator comprising thiourea and an organic base are added to a thiazide dione monomer solution. The co-catalyst converts the sulfide anion at the end of the growing chain formed during the polymerization of the thiazide dione monomer into a thiourea anion, thereby causing the thiazide dione monomer to undergo ring-opening polymerization to obtain a polythioester amide polymer. The thiourea has the following structural formula, where R1 and R2 are substituted or unsubstituted six-membered cycloalkanes or benzene rings. ； The organic base includes one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and organophosphononitrile bases, wherein the acidity coefficient of the organic base is greater than 10, and the difference in acidity coefficient between the thiourea and the organic base is less than 5.
0.
2. The method according to claim 1, wherein, The concentration range of the thiamethoxam monomer solution is 1.5 mol / L to 2.5 mol / L; The molar ratio of the thiazidedione monomer, the cocatalyst, and the initiator is 100:1:
1.
3. The method according to claim 1, wherein, The polymerization reaction is carried out at a temperature of 25–30°C.
4. The method according to claim 1, wherein, The thiazine dione monomer is selected from one of the following structural formulas: 。 5. The method according to claim 1, wherein, The initiator includes benzyl mercaptan; The solvent includes one of N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, chloroform, and acetonitrile.
6. The method according to claim 1, further comprising adding a precipitating agent after the polymerization reaction occurs to precipitate the polythioester amide polymer, wherein, The precipitant includes diethyl ether.
7. A method for depolymerizing polythioester amide, comprising: The polysulfate amide prepared by any one of claims 1 to 6 is dissolved in a solvent, an organic base catalyst is added, and the polysulfate amide is depolymerized and the thiazine dione monomer is recovered under anhydrous and oxygen-free conditions.
8. The method according to claim 7, wherein, The concentration of the polysulfate amide solution is not higher than 0.05 mol / L, the feed ratio of polysulfate amide to organic base is 100:1, and the reaction time is 10 min.