Preparation of saturated carbon chain polymer and method for chemical degradation recovery thereof

Abstract

The application discloses a preparation method and a chemical degradation and recovery method of a novel saturated carbon chain polymer. 3 )‑hydrogen bond carbon nucleophile 1 or 3 as an initiator, a push-pull electron system cyclobutane 2 as a monomer, and a tin tetrachloride and an organic base synergistic catalyst is used to carry out homopolymerization or copolymerization reaction, and after sedimentation, collection and drying, the target polymer I or II can be obtained; a synthesis route is shown in the following: the application applies a synergistic catalyst system composed of tin tetrachloride and an organic base to catalyze the ring-opening polymerization of the push-pull electron system cyclobutane. The polymer obtained by the application has good thermal stability, and can be degraded into small molecular compounds through SnCl4 catalytic depolymerization, and has application prospects in the industrial preparation of green polymer materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis technology, specifically relating to a novel method for the preparation of saturated carbon chain polymers and their chemical degradation and recycling. Background Technology

[0002] Saturated carbon-chain polymers are a crucial class of polymeric materials, playing a vital role in modern life and production. However, the non-polar nature of traditional saturated carbon-chain polymers (such as polyethylene and polypropylene) limits their further application in many fields. Introducing a small number of polar functional groups into saturated carbon-chain polymers can significantly improve their surface properties, flexibility, adhesion, and blendability with other polymeric materials. Currently, strategies for introducing polar functional groups are still relatively limited, mainly focusing on transition metal-catalyzed copolymerization of olefins and polar monomers, which suffers from the limitation of low polar monomer insertion rates. Furthermore, saturated carbon-chain polymers typically exhibit high stability, making them difficult to effectively degrade and recycle after use, resulting in insufficient environmental friendliness and sustainability.

[0003] Ring-opening polymerization of functionalized cycloalkane monomers is an effective strategy for preparing saturated carbon chain polymers. Its advantage lies in the fact that each repeating unit of the polymer contains multiple substituents, achieving a 100% functional group incorporation rate. For example, the ring-opening polymerization of polysubstituted cyclopropanes is a relatively mature polymerization system, mainly due to the high stability of cyclopropane molecules and their high regioselectivity and stereoselectivity in the ring-opening reaction. However, the ring-opening polymerization of cyclobutane, an analogue of cyclopropane, has been less studied because cyclobutane lacks stability, readily undergoes a reverse [2+2] reaction to generate two molecules of olefin derivatives, and has low stereoselectivity in its ring-opening reaction.

[0004] The synergistic control of dual-catalytic systems has been proven to be an effective strategy for increasing polymerization rates and suppressing side reactions. It enables precise control of the ring-opening polymerization of various cyclic monomers (such as ethylene oxide, lactide, and caprolactone) to prepare high-molecular-weight polymer materials with narrow distributions. Given the significant scientific value of cyclobutane ring-opening polymerization and the current technological bottlenecks, there is an urgent need to develop a novel dual-catalytic system to achieve efficient polymerization and chemical degradation and recovery of cyclobutane. Summary of the Invention

[0005] The purpose of this invention is to provide a novel method for preparing saturated carbon chain polymers and their chemical degradation and recycling. Specifically, the method involves preparing saturated carbon chain polymers by ring-opening polymerization of cyclobutane using a push-pull electron system, while simultaneously achieving chemical degradation and recycling of the polymers under relatively mild conditions, thereby solving the aforementioned problems existing in the prior art.

[0006] The present invention discloses a method for preparing a novel saturated carbon chain polymer, using a polymer containing acidic carbon (sp). 3Using carbon nucleophiles 1 or 3 with hydrogen bonds as initiators, and cyclobutane 2 with a push-pull electron system as monomer, homopolymerization or copolymerization is carried out under the synergistic catalysis of tin tetrachloride (SnCl4) and organic base. After sedimentation, collection and drying, the target polymer I or II can be obtained.

[0007] The synthesis route is shown below:

[0008] (1)

[0009] (2)

[0010] (3)

[0011] (4)

[0012] R 1 R 1′ Selected from aryl or ethoxy; R 2 R 3 R 4 R 5 R 6 Each group can be independently selected from ethoxycarbonyl, cyano, acetyl, diethoxyphosphono, halogen, phenyl, or carbamoyl; n (including n1, n2, n3, n4, and n′) is a positive integer representing the degree of polymerization.

[0013] In the above synthetic routes, routes (1) and (2) represent bilaterally initiated and unilaterally initiated polymerization reactions, respectively. Unilateral or bilateral polymerization is initiated by acidic carbon (sp) in the initiator. 3 The number of hydrogen bonds is determined by the number of hydrogen bonds, and therefore can be artificially controlled.

[0014] Routes (3) and (4) represent different polymerization methods, namely random copolymerization and block copolymerization, respectively. The introduction of 2' in route (3) is to demonstrate R in compound 2. 1 Choose different substituents (i.e., R) 1 and R 1′ When both exist simultaneously and are different, the obtained polymer I is a random copolymer. Route (4) controls the presence of different substituents (i.e., R). 1 and R 1′ The timing of the addition of compounds 2 (i.e., 2 and 2') (which are different from each other) resulted in a block copolymer product. Therefore, strictly speaking, the target products of routes (3) and (4) both fall within the structural scope of polymer I.

[0015] The organic base is selected from 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 4-dimethylaminopyridine (DMAP), triethylamine (NEt3), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

[0016] Specifically, the steps include the following:

[0017] In an N2 glove box, rapidly add the magnetic initiator, small molecule initiator 1 or 3 or polymer initiator I, monomer 2, organic base, and anhydrous organic solvent sequentially to a dry 10 mL Schlenk reaction tube. Seal the Schlenk tube and remove it from the glove box. Stir the reaction at 0–50 °C for 0.5–24 hours. Analyze the reaction by hydrogen nuclear magnetic resonance (HMR) spectroscopy. 1 The monomer conversion was analyzed by ¹H NMR. After the polymerization reaction reached the endpoint, the reaction mixture was slowly added to 10 mL of n-hexane for precipitation. The collected polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum drying oven at 50 °C for 24 hours to obtain the target product.

[0018] The organic solvent is selected from acetonitrile, N,N-dimethylacetamide, tetrahydrofuran, toluene, or dichloromethane.

[0019] The molar ratio of tin tetrachloride (SnCl4) to cyclobutane 2 in the push-pull electron system is 0.02:1–0.1:1; the molar ratio of organic base to cyclobutane 2 in the push-pull electron system is 0.02:1–0.1:1; and the molar ratio of initiator 1 or 3 to cyclobutane 2 in the push-pull electron system is 0.005:1–0.05:1.

[0020] This invention discloses a chemical degradation and recovery method for saturated carbon chain polymers, using tin tetrachloride (SnCl4) as a catalyst. Polymer I or II is dissolved in acetonitrile, and the reaction is carried out with stirring at rt–100°C for 5–24 hours. The number-average molecular weight (Mn) of the polymer is analyzed by gel permeation chromatography (GPC). n ) and its distribution The changes were observed, and the small molecule degradation product 4 was finally obtained by column chromatography.

[0021] The chemical degradation and recycling route is shown below:

[0022]

[0023] In the above formula: R 1 Selected from aryl or ethoxy; R 2 R 3 R 4 R 5 R 6Each group is independently selected from ethoxycarbonyl, cyano, acetyl, diethoxyphosphono, halogen, phenyl, or carbamoyl; n is a positive integer representing the degree of polymerization.

[0024] in:

[0025] The molar ratio of tin tetrachloride (SnCl4) to polymer I or II repeating units is 0.02:1–0.2:1.

[0026] This invention provides a novel method for the preparation and chemical degradation and recycling of saturated carbon chain polymers through a synergistic catalytic strategy of metal Lewis acids and organic bases. This invention utilizes acidic carbon (sp...) 3 Using hydrogen-based carbon nucleophile 1 and electron-pulling cyclobutane 2 as initiators and monomers, tin tetrachloride (SnCl4) as a Lewis acid catalyst, and amine compounds as organic bases, polycyclobutane I or II was rapidly and efficiently synthesized via ring-opening polymerization. The purified polymers I or II can be degraded into small molecule compound 4 under tin tetrachloride / acetonitrile conditions. This invention not only successfully develops a saturated carbon chain polymer material with good thermal stability but also enables chemical degradation and recycling under mild conditions. Detailed Implementation

[0027] Example 1: Preparation of polymer Iaa by ring-opening polymerization of monomer 2a initiated by diethyl malonate 1a.

[0028]

[0029] In a glove box, a magnetic flux, monomer 2a (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.004 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH₂Cl₂, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iaa. White solid, 102 mg, M n =24kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =233℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =87℃.

[0030] Example 2: Preparation of polymer Iba by ring-opening polymerization of monomer 2a initiated by malononitrile 1b.

[0031]

[0032] In a glove box, a magnetic stir bar, monomer 2a (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), malononitrile 1b (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH₂Cl₂, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iba. White solid, 106 mg, M n =21kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =232℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =87℃.

[0033] Example 3: Preparation of polymer Ica by ring-opening polymerization of monomer 2a initiated by acetylacetone 1c.

[0034]

[0035] In a glove box, a magnetic flux, monomer 2a (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), acetylacetone 1c (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH₂Cl₂, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Ica. White solid, 98 mg, M n =20kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =233℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =87℃.

[0036] Example 4: Preparation of polymer Ida by ring-opening polymerization of monomer 2a initiated by diethyl acetone phosphonate 1d.

[0037]

[0038] In a glove box, a magnetic flux, monomer 2a (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl pyruvate phosphonate 1d (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Ida. White solid, 92 mg, M n =11kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =231℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =86℃.

[0039] Example 5: Preparation of polymer IIea by ring-opening polymerization of monomer 2a initiated by diethyl 2-bromomalonate 1e.

[0040]

[0041] In a glove box, a magnetic flux, monomer 2a (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl 2-bromomalonate 1e (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH₂Cl₂, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer ILea. White solid, 93 mg, M n =9.8kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =231℃, the polymer glass transition temperature T was determined by differential scanning calorimetry.g =85℃.

[0042] Example 6: Preparation of polymer IIfa by ring-opening polymerization of monomer 2a initiated by N-tert-butoxycarbonyl-3-phenyloxyindole 1f.

[0043]

[0044] In a glove box, a magnetic flux, monomer 2a (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), N-tert-butoxycarbonyl-3-phenylindole 1f (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL) were added sequentially to a dry 10 mL Schlenk tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer IIfa. White solid, 100 mg, M n =9.6kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =232℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =86℃.

[0045] Example 7: Preparation of polymer Iab by ring-opening polymerization of monomer 2b initiated by diethyl malonate 1a.

[0046]

[0047] In a glove box, a magnetic stir bar, monomer 2b (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.008 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iab. White solid, 101 mg, M n =16kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d5％ =274℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =81℃.

[0048] Example 8: Preparation of polymer Iac by ring-opening polymerization of monomer 2c initiated by diethyl malonate 1a.

[0049]

[0050] In a glove box, a magnetic flux, monomer 2c (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.008 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH₂Cl₂, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iac. White solid, 95 mg, M n =8.1kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =329℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =73℃.

[0051] Example 9: Preparation of polymer Iad by 2d ring-opening polymerization of monomers initiated by diethyl malonate 1a.

[0052]

[0053] In a glove box, a magnetic flux, monomer 2d (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.008 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iad. White solid, 104 mg, M n =18kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =236℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =62℃.

[0054] Example 10: Preparation of polymer Iae by ring-opening polymerization of monomer 2e initiated by diethyl malonate 1a.

[0055]

[0056] In a glove box, a magnetic flux, monomer 2e (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.008 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iae. White solid, 88 mg, M n =5.7kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =306℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =85℃.

[0057] Example 11: Preparation of polymer Iaf by ring-opening polymerization of monomer 2f initiated by diethyl malonate 1a.

[0058]

[0059] In a glove box, a magnetic flux, monomer 2f (0.4 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.02 mmol), and tin tetrachloride (0.02 mmol, 1.0 M in CH2Cl2, 20 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iaf. White solid, 88 mg, M n=4.8kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =223℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =46℃.

[0060] Example 12: Preparation of random copolymer Iaa-ran-Iae

[0061]

[0062] In a glove box, a magnetic stir bar, monomer 2a (0.2 mmol), monomer 2e (0.2 mmol), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), diethyl malonate 1a (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL) were added sequentially to a dry 10 mL Schlenk reaction tube. The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iaa-ran-Iae. White solid, 111 mg, M n =8.0kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =242℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =62℃.

[0063] Example 13: Preparation of block copolymer Iac-b-Iaa-b-Iac

[0064]

[0065] In a glove box, a magnetic magnet, monomer 2c (0.2 mmol), and polymer Iaa (M) were added sequentially to a dry 10 mL Schlenk reaction tube. n =5.1 kDa, 51 mg), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL). The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum drying oven at 50 °C for 24 hours to obtain the polymer Iac-b-Iaa-b-Iac. White solid, 110 mg, M n =11kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =268℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =59℃.

[0066] Example 14: Preparation of block copolymer Iad-b-Iaa-b-Iad

[0067]

[0068] In a glove box, magnetic flux, monomer 2d (0.2 mmol), and polymer Iaa (M) were added sequentially to a dry 10 mL Schlenk reaction tube. n =5.1 kDa, 51 mg), anhydrous acetonitrile (0.4 mL), DBU (0.02 mmol), and tin tetrachloride (0.04 mmol, 1.0 M in CH2Cl2, 40 μL). The Schlenk tube was sealed and removed from the glove box, then stirred at 50 °C for 30 minutes. 1 ¹H NMR analysis showed a monomer conversion of 99%. The reaction mixture was slowly added to 10 mL of n-hexane. The precipitated polymer was washed with n-hexane (5 mL × 2) and dried in a vacuum oven at 50 °C for 24 hours to obtain polymer Iad-b-Iaa-b-Iad. White solid, 97 mg, M n =14kDa, Thermogravimetric analysis determined the polymer decomposition temperature T d 5％ =233℃, the polymer glass transition temperature T was determined by differential scanning calorimetry. g =53℃.

[0069] Example 15: Chemical degradation and recovery of polymer Iaa

[0070]

[0071] A magnetic magnet and polymer Iaa (M) were added sequentially to a 10 mL Schlenk reaction tube. n=14kDa, 30mg), anhydrous acetonitrile (0.3mL), and tin tetrachloride (0.02mmol, 1.0M in CH2Cl2, 20μL). The Schlenk tube was sealed and removed from the glove box, then stirred at 100°C for 5 hours. Samples were taken using a 1mL syringe. 1 ¹H NMR and gel permeation chromatography (GPC) analyses were performed, and finally, column chromatography was used to separate the small molecule compound 4a, a colorless oil, 14.8 mg, 50% yield. 1 HNMR(500MHz,Chloroform-d)δ7.26(dd,J=6.8,2.0Hz,3H),6.87–6.77(m,2H),6.42(d,J=15.9Hz,1H),6.01(dt,J=15.7,7.2 Hz,1H),4.20(qd,J=7.2,2.9Hz,4H),3.80(s,3H),3.47(t,J=7.5Hz,1H),2.78(td,J=7.4,1.4Hz,2H),1.26(t,J=7.1Hz,8H). 13 C NMR (126MHz, Chloroform-d) δ169.0,159.0,132.2,129.9,127.3,123.3,113.9,61.5,55.3,52.2,32.3,14.1.

[0072] Example 16: Chemical degradation and recovery of polymer Iab

[0073]

[0074] A magnetic magnet and polymer Iab (M) were added sequentially to a 10 mL Schlenk reaction tube. n =15kDa, 30mg), anhydrous acetonitrile (0.3mL), and tin tetrachloride (0.02mmol, 1.0M in CH2Cl2, 20μL). The Schlenk tube was sealed and removed from the glove box, then stirred at 100°C for 5 hours. Samples were taken using a 1mL syringe. 1 ¹H NMR and gel permeation chromatography (GPC) analyses were performed, and finally, column chromatography was used to separate the small molecule compound 4b, a colorless oil, 15.6 mg, 52% yield. 1HNMR(500MHz,Chloroform-d)δ7.26–7.22(m,2H),6.86–6.76(m,2H),6.45–6.37(d,J=15.8,1H),6.00(dt,J=15.8,7.2Hz,1H),4.20(qd,J =7.1,1.9Hz,4H),4.02(q,J=7.0Hz,2H),3.47(t,J=7.5Hz,1H),2.77(td,J=7.4,1.4Hz,2H),1.40(t,J=7.0Hz,3H),1.25(t,J=7.1Hz,6H). 13 CNMR(126MHz,Chloroform-d)δ168.0,157.4,131.2,128.7,126.3,122.2,113.4,62.4,60.4,51.2,31.2,13.8,13.1.

[0075] Example 17: Chemical degradation and recovery of polymer Iac

[0076]

[0077] A magnetic magnet and polymer Iaa (M) were added sequentially to a 10 mL Schlenk reaction tube. n =10 kDa, 30 mg), anhydrous acetonitrile (0.3 mL), and tin tetrachloride (0.02 mmol, 1.0 M in CH2Cl2, 20 μL). The Schlenk tube was sealed and removed from the glove box, then stirred at 100 °C for 5 hours. Samples were taken using a 1 mL syringe. 1 ¹H NMR and gel permeation chromatography (GPC) analyses were performed, and finally, column chromatography was used to separate the small molecule compound 4c, a colorless oil, 12.4 mg, with a yield of 41%. 1 HNMR(500MHz,Chloroform-d)δ7.46–7.30(m,5H),7.28–7.23(m,2H),6.96–6.83(m,2H),6.49–6.35(d,J=15.7,1H),6.01(dt,J=15 .7,7.2Hz,1H),5.06(s,2H),4.20(qd,J=7.1,2.1Hz,4H),3.47(t,J=7.5Hz,1H),2.77(td,J=7.4,1.4Hz,2H),1.26(t,J=7.1Hz,6H). 13C NMR(126MHz,Chloroform-d)δ169.0,158.2,137.0,132.2,130.2,128.6,128.0,127.5,127.3,123.5,114.9,70.0,61.5,52.2,32.3,14.1。

Claims

1. A method for preparing a saturated carbon chain polymer, characterized in that: Containing acidic carbon (sp) 3 Using carbon nucleophiles 1 or 3 (with hydrogen bonds) as initiators and cyclobutane 2 (with an electron-pull system) as a monomer, homopolymerization or copolymerization is carried out under the synergistic catalysis of tin tetrachloride and organic bases. After sedimentation, collection, and drying, the target polymer I or II can be obtained. The synthetic route is shown below: (1) (2) Where: R 1 Selected from one of aryl and ethoxy groups; R 2 R 3 R 4 R 5 R 6 Each group can be independently selected from ethoxycarbonyl, cyano, acetyl, diethoxyphosphono, halogen, phenyl, or carbamoyl; n is a positive integer representing the degree of polymerization.

2. The preparation method according to claim 1, characterized in that: Target polymer I or II includes products of random copolymerization and block copolymerization.

3. The preparation method according to claim 1, characterized in that: The organic base is selected from 1,8-diazabicyclo[5.4.0]undec-7-ene, 4-dimethylaminopyridine, triethylamine, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the organic base to the push-pull electron system cyclobutane 2 is 0.02:1–0.1:

1.

5. The preparation method according to claim 1, characterized in that: The organic solvent is selected from acetonitrile, N,N-dimethylacetamide, tetrahydrofuran, toluene, or dichloromethane.

6. The preparation method according to claim 1, characterized in that: The molar ratio of tin tetrachloride to cyclobutane 2 in the push-pull electron system is 0.02:1–0.1:

1.

7. The preparation method according to claim 1, characterized in that: The molar ratio of initiator 1 or 3 to cyclobutane 2 in the push-pull electron system is 0.005:1-0.05:

1.

8. A method for the chemical degradation and recycling of saturated carbon chain polymers prepared by any one of claims 1–7, characterized in that: Using tin tetrachloride as a catalyst, polymer I or II was dissolved in acetonitrile and reacted with stirring at room temperature to 100°C for 5–24 hours. The small molecule degradation product 4 was obtained by column chromatography.

9. The method according to claim 8, characterized in that: The molar ratio of tin tetrachloride to polymer I or II repeating units is 0.02:1–0.2:1.

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