Controllable degradation method of vinyl polymer

Abstract

The invention discloses a controllable degradation method of a vinyl polymer, which comprises the following steps: (S1) carrying out ring-opening reaction of cyclobutane on a vinyl polymer shown in a formula a under the stimulation of mechanical force to obtain an activated vinyl polymer shown in a formula b; and (S2) hydrolyzing the activated vinyl polymer as shown in the formula b in the step (S1) in an acidic environment to realize degradation of the vinyl polymer. According to the invention, a strategy of editing the main chain of the vinyl polymer by using mechanical force is adopted, so that the integrity and stability of a polymer skeleton are ensured, meanwhile, a breakable group in a cyclobutane unit can be introduced into the main chain in situ, and the breakable group can be destroyed through reactions such as hydrolysis and the like, so that effective degradation of the vinyl polymer is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer synthesis, and particularly relates to a controllable degradation method of a vinyl polymer, and particularly relates to a controllable degradation method of a vinyl polymer based on mechanical force editing. BACKGROUND

[0002] The vinyl polymer main chain is connected by inert carbon-carbon (C-C) single bonds, which provides excellent stability for it. In the face of urgent environmental problems and sustainable development, the demand for degradable polymers has surged in academia and industry. At present, one of the strategies to solve the degradation problem of vinyl polymers is to introduce cleavable functional groups into the polymer backbone, and the most effective and most widely used method is to copolymerize commercial vinyl monomers with other special monomers through free radicals. In the prior art, cyclic ketene acetal (CKA), macrocyclic thiolactone (DOT), macrocyclic allyl sulfone / sulfide (MAS), isocyanate and alpha-lipoic acid have been used as comonomers to introduce degradable units such as ester groups, thioester groups, disulfides and carbonyl groups into the polymer backbone. However, although the above methods effectively solve the problem of polymer degradation by introducing cleavable groups, the inherent instability of these cleavable groups increases the risk of damaging the properties of the polymer during application, limiting its more extensive application. Therefore, it is urgent to develop a new strategy to achieve controllable degradation of vinyl polymers. SUMMARY

[0003] The purpose of the present application is to solve the problems existing in the prior art, and to provide a controllable degradation method of a vinyl polymer based on mechanical force editing. The present application edits the vinyl polymer main chain by mechanical force, introduces cleavable groups such as imide and ester groups into the main chain in situ, and finally breaks the cleavable groups by hydrolysis reaction to efficiently achieve the degradation of the vinyl polymer. Therefore, the method of the present application can introduce degradable groups in situ while ensuring the integrity and stability of the polymer backbone, and provides a reliable method for realizing the degradation of the vinyl polymer.

[0004] To achieve the above purpose, the technical scheme adopted by the present application is:

[0005] A controllable degradation method of a vinyl polymer, the method comprising:

[0006] (S1) subjecting a vinyl polymer represented by formula a to ring-opening reaction of cyclobutane under mechanical force stimulation to obtain an activated vinyl polymer represented by formula b;

[0007] (S2) hydrolyzing the activated vinyl polymer represented by formula b in step (S1) in an acidic environment to realize the degradation of the vinyl polymer;

[0008]

[0009] In formula a and formula b, R1, R2 and R3 are the same or different, and are independently selected from H, C 1-20 alkyl;

[0010] R4, R5 and R6 are the same or different, and are independently selected from H, -C(=O)OC 1-20 alkyl, -C 0-6 alkylene-C 6-20 aryl, halogen, -COOH, -C(=O)NR 11 R 12 , -CN, -O(=O)CC 1-20 alkyl;

[0011] Ring A is a 3- to 10-membered ring, for example, a 3-membered ring, a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, an 8-membered ring, a 9-membered ring or a 10-membered ring; R7 is R a substituted heteroatom E, wherein the heteroatom E is selected from boron, nitrogen, silicon, phosphorus atom; or R7 is a heteroatom B, the heteroatom B is oxygen or sulfur; Ring A is further substituted with one or more R8, R a selected from H, -C 1-20 alkyl, -C(=O)OC 1-20 alkyl, -C 0-6 alkylene-C 6-20 aryl, halogen, -COOH, -C(=O)NR 11 R 12 , -CN, -O(=O)CC 1-20 alkyl, R8 is a carbonyl or a thiocarbonyl group;

[0012] R 11 and R 12 are the same or different, and are independently selected from H, C 1-12 alkyl;

[0013] wherein, 1≤m:k≤500; 20≤m≤1000; 20≤n≤2000.

[0014] According to an embodiment of the present application, the mechanism of the controllable degradation method of the ethylene-based polymer is as follows:

[0015]

[0016] p is 1≤p≤100, and p is less than m or n;

[0017] R1, R2, R3, R4, R5, R6, R7, A have the meanings as described above.

[0018] According to an embodiment of the present application, in step (S1), the method of applying mechanical force comprises at least one of ultrasonic method, ball milling method. Preferably, the time of mechanical force stimulation is 30 s-72 h, preferably 6-72 h. Preferably, the vibration frequency of mechanical force is 5-50 kHz, preferably 15-30 kHz.

[0019] According to an embodiment of the present application, in step (S1), the mechanical force stimulation is performed using a vinyl polymer solution of formula a, which is an organic solvent solution of the vinyl polymer of formula a, the organic solvent being selected from at least one of dimethyl sulfoxide, N,N-dimethylformamide, dichloromethane, 1,2-dichloroethane, chloroform, acetone, ethyl acetate, benzene, toluene, tetrahydrofuran, diethyl ether, acetonitrile, 1,4-dioxane.

[0020] Preferably, the concentration of the vinyl polymer solution of formula a is 0.01-50 mg / mL, preferably 0.5-20 mg / mL.

[0021] According to an embodiment of the present application, in step (S1), the temperature of ring-opening reaction is 0-120 °C, for example, 0 °C, 20 °C, 40 °C, 50 °C, 80 °C, 100 °C or 120 °C.

[0022] According to an embodiment of the present application, in step (S2), the pH of acidic environment is <7, the temperature of hydrolysis is 0-250 °C, preferably 20-100 °C, and more preferably 30-80 °C; the time of hydrolysis is 6-48 h, preferably 12-24 h.

[0023] According to an embodiment of the present application, in step (S2), the acidic environment is performed in an acidic solution, for example. The acidic solution is, for example, aqueous trifluoroacetic acid solution, aqueous hydrogen chloride solution, aqueous acetic acid solution, etc.

[0024] Preferably, the concentration of the activated vinyl polymer of formula b in the acidic solution is 0.01-50 mg / mL, preferably 0.5-20 mg / mL.

[0025] According to an embodiment of the present application, R1, R2 and R3 are the same or different, and are independently selected from H, C 1-12 alkyl; and more preferably H, C 1-6 alkyl.

[0026] According to an embodiment of the present application, R4, R5 and R6 are the same or different, and are independently selected from H, -C(=O)OC 1-12 alkyl, -C 0-6 alkylene--C 6-14 aryl, halogen, -COOH, -C(=O)NR 11 R12 , -CN, -O(O=)CC 1-12 alkyl; further preferred H, -C(=O)OC 1-6 alkyl, -C 0-6 alkylene -C 6-14 aryl, halogen, -COOH, -C(=O)NR 11 R 12 , -CN, -O(O=)CC 1-6 alkyl;

[0027] Preferably, R 11 and R 12 are independently of each other selected from H, C 1-6 alkyl.

[0028] According to embodiments of the present application, the heteroatom E is preferably nitrogen; the heteroatom B is preferably oxygen.

[0029] According to embodiments of the present application, R a is selected from H, C 1-12 alkyl, -C(=O)OC 1-12 alkyl, -C 1-6 alkylene -C 6-14 aryl, halogen, -COOH, -C(=O)NR 11 R 12 , -CN, -O(O=)CC 1-12 alkyl, R 11 and R 12 are independently of each other selected from H, C 1-6 alkyl; preferably, R a is selected from H, C 1-6 alkyl, -C(=O)OC 1-6 alkyl, -C 1-6 alkylene -C 6-14 aryl, halogen, -COOH, -CONR 11 R 12 , -CN, -O(O=)CC 1-6 alkyl.

[0030] According to embodiments of the present application, step (S1) further comprises a post-treatment of the activated vinyl polymer of formula b, removing the solvent from the activated vinyl polymer of formula b, such as distillation removal, further such as removal by distillation under reduced pressure.

[0031] According to embodiments of the present application, 10 < m:k < 500.

[0032] According to embodiments of the present application, 20 < m < 500.

[0033] According to an embodiment of the present application, 50≤n≤2000.

[0034] According to an embodiment of the present application, 1≤p≤60.

[0035] According to an embodiment of the present application, the vinyl polymer represented by formula a is prepared specifically by a method comprising the following steps:

[0036] (1) mixing a vinyl monomer represented by formula I, a cyclobutenyl monomer represented by formula II, a RAFT agent represented by formula III and an organic solvent under anhydrous and oxygen-isolated conditions to form a pre-reaction mixture;

[0037] (2) reacting the pre-reaction mixture of step (1) under a light source with a predetermined wavelength and light intensity to prepare a vinyl polymer represented by formula a;

[0038]

[0039]

[0040] wherein R1, R2, R3, R4, R5, R6, R7, A have the meanings as described above;

[0041] R8is selected from one of substituted or unsubstituted C 1-20 alkyl, substituted or unsubstituted -C 0-6 alkylene-C 6-20 aryl, the substituents R c are halogen, -COOH, -CN, -N-(C(=O)-R 13 )2, -C(=O)NR 14 R 15 ; R 13 , R 14 and R 15 are identical or different from each other and are independently selected from H, C 1-12 alkyl;

[0042] R9is selected from one of substituted or unsubstituted C 1-20 alkyl, substituted or unsubstituted -C 0-6 alkylene-C 6-20 aryl, substituted or unsubstituted -S-C 1-20 alkyl, substituted or unsubstituted -O-C 1-20 alkyl, substituted or unsubstituted -NH-C 1-20 alkyl; wherein the substituents R b are -N-(C(=O)-R 13 )2, -C(=O)NR 14 R 15 , -C(=O)OC 1-12alkyl, -C 1-12 alkyl-COOH, after dehydration, anhydride, -OC 1-12 alkyl, -COOH, and the like; R 13 , R 14 and R 15 are the same or different, each independently selected from the group consisting of H, C 1-12 alkyl.

[0043] According to embodiments of the present application, the vinyl monomer of Formula I is at least one of a methacrylate (e.g., methacrylate), an acrylate (e.g., acrylate), a styrene (e.g., styrene), a vinyl chloride, an acrylic acid, an acrylamide, an acrylonitrile, and a vinyl acetate; for example, the vinyl monomer of Formula I is at least one of methyl acrylate, N,N-dimethyl acrylamide, styrene, and the like.

[0044] According to embodiments of the present application, the organic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, dichloromethane, 1,2-dichloroethane, chloroform, acetone, ethyl acetate, benzene, toluene, tetrahydrofuran, diethyl ether, acetonitrile, 1,4-dioxane;

[0045] According to embodiments of the present application, the cyclobutenyl monomer of Formula II is, for example, a succinimide cyclobutene.

[0046] According to embodiments of the present application, in Formula III, R8is selected from one of a substituted or unsubstituted C 1-12 alkyl, a substituted or unsubstituted C 0-6 alkylene-C 6-14 aryl; further preferred is one of a substituted or unsubstituted C 1-6 alkyl, a substituted or unsubstituted C 0-6 alkylene-C 6-14 aryl. Preferably, the substituents R c are halogen, -COOH, -CN, -N-(C(=O)-R 13 )2, -C(=O)NR 14 R 15 ; R 13 , R 14 and R 15 are the same or different, each independently selected from the group consisting of H, C 1-6 alkyl.

[0047] According to embodiments of the present application, in Formula III, R9is a substituted or unsubstituted C 1-12 alkyl, a substituted or unsubstituted C 0-6 alkylene-C 6-14 aryl, a substituted or unsubstituted -S-C 1-12 alkyl, a substituted or unsubstituted -O-C1-12 alkyl, substituted or unsubstituted -NH-C 1-12 alkyl; preferably, substituted or unsubstituted C 1-6 alkyl, substituted or unsubstituted C 0-6 alkylene-C 6-14 aryl, substituted or unsubstituted -S-C 1-6 alkyl, substituted or unsubstituted -O-C 1-6 alkyl, substituted or unsubstituted -NH-C 1-6 alkyl.

[0048] Preferably, the substituent R b is -N-(C(=O)-R 13 )2, -C(=O)NR 14 R 15 , -C(=O)OC 1-6 alkyl, -C 1-6 alkyl-COOH after dehydration, -OC 1-6 alkyl, -COOH, etc.; R 13 , R 14 and R 15 are the same or different, and are independently selected from H, C 1-6 alkyl.

[0049] According to an embodiment of the present application, the RAFT agent shown in formula III is, for example, 2-[dodecylsulfanyl(thiocarbonyl)thio]propanoic acid.

[0050] According to an embodiment of the present application, the molar ratio of the vinyl monomer: the cyclobutenyl monomer: the RAFT agent is (10-10000):(10-10000):1; preferably (100-2000):(100-1000):1.

[0051] According to an embodiment of the present application, the concentration of the RAFT agent in the organic solvent is 0.00001-10 mol / L, preferably 0.001-0.01 mol / L.

[0052] According to an embodiment of the present application, in step (2), the light intensity of the light source is not less than 0.1 W / cm -2 , preferably 1-20 W / cm -2 ; the wavelength range is 200-700 nm, preferably 420-460 nm.

[0053] The beneficial effects of the present application are:

[0054] (1) The vinyl polymer structure represented by formula a of the present application is clear, the polymer main chain contains cyclobutane units, the insertion ratio of the cyclobutane units and the molecular weight of the obtained vinyl polymer can be controlled by adjusting the feeding ratio of the vinyl monomer and the cyclobutene monomer.

[0055] (2) The chain end of the vinyl polymer prepared by the present application contains a thiocarbonyl sulfur group, so that the polymer has an active feature, and can be subjected to reinitiated polymerization.

[0056] (3) In the prior art, the main chain structure of free radical polymerization is basically C-C bond, which cannot be hydrolyzed; and because the active chain end is carbon free radical in the free radical polymerization process, it is very difficult to directly introduce ester bond and other hydrolysis groups into the polymer main chain during the polymerization process. The present application adopts the strategy of mechanical force editing vinyl polymer main chain, which can introduce the breakable group in the cyclobutane unit to the main chain in situ while ensuring the integrity and stability of the polymer skeleton, and can destroy the breakable group through hydrolysis and other reactions to realize the effective degradation of the vinyl polymer.

[0057] Term definition and explanation

[0058] Unless otherwise specified, the terms and descriptions in the context of the present application have the meanings described below.

[0059] The term "halogen" means fluorine, chlorine, bromine or iodine.

[0060] The term "C 1-20 "alkyl" is understood to mean a straight-chain or branched saturated monovalent hydrocarbon group having 1 to 20 carbon atoms. For example, "C 1-12 "alkyl" means a straight-chain and branched alkyl group having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms, "C 1-6 "alkyl" means a straight-chain and branched alkyl group having 1, 2, 3, 4, 5 or 6 carbon atoms. The alkyl group is, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl and the like or their isomers.

[0061] The term "C 6-20 "aryl" is understood to mean preferably a monovalent aromatic or partially aromatic monocyclic, bicyclic or tricyclic hydrocarbon ring having 6 to 20 carbon atoms, preferably "C 6-14 "aryl". The term "C6-14 "Aryl" is understood to preferably mean a monovalent aromatic or partially aromatic, monocyclic, bicyclic or tricyclic hydrocarbon ring ("C 6-14 ("C9 aryl"), such as, for example, indanyl or indenyl, or a ring having 10 carbon atoms ("C 10 ("C9 aryl"), such as, for example, indanyl or indenyl, or a ring having 10 carbon atoms ("C 13 ("C9 aryl"), such as, for example, indanyl or indenyl, or a ring having 10 carbon atoms ("C 14 ("C9 aryl"), such as, for example, indanyl or indenyl, or a ring having 10 carbon atoms ("C 6-20 When the C 6-20 When the C BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 Figure 1 is a graph of the nuclear magnetic resonance hydrogen spectrum (1H NMR, CDC13) of the succinimide cyclobutene monomer in Example 1; 1 H NMR, CDC13) of the copolymerization product in Example 2;

[0063] Figure 2 Figure 1 is a graph of the nuclear magnetic resonance hydrogen spectrum (1H NMR, CDC13) of the succinimide cyclobutene monomer in Example 1; 1 H NMR, CDC13) of the copolymerization product in Example 2;

[0064] Figure 3 Figure 1 is a graph of the nuclear magnetic resonance hydrogen spectrum (1H NMR, CDC13) of the succinimide cyclobutene monomer in Example 1; 1 H NMR, CDC13) of the copolymerization product in Example 2;

[0065] Figure 4 Figure 1 is a graph of the nuclear magnetic resonance hydrogen spectrum (1H NMR, CDC13) of the succinimide cyclobutene monomer in Example 1; 1 H NMR, CDC13) of the copolymerization product in Example 2;

[0066] Figure 5 Figure 1 is a graph of the nuclear magnetic resonance hydrogen spectrum (1H NMR, CDC13) of the succinimide cyclobutene monomer in Example 1;

[0067] Figure 6 Figure 1 is a graph of the nuclear magnetic resonance hydrogen spectrum (1H NMR, CDC13) of the succinimide cyclobutene monomer in Example 1; DETAILED DESCRIPTION

[0068] The technical solutions of the present application will be further described in detail below in conjunction with specific examples. It should be understood that the following examples are only illustratively described and explained, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is encompassed within the scope intended to be protected by the present application.

[0069] The starting materials and reagents used in the following examples are commercially available or can be prepared by known methods unless otherwise stated.

[0070] Example 1: Synthesis of succinimidyl cyclobutene monomer

[0071] N-benzyl maleimide (22.5 g, 120 mmol) and (E)-1,2-dichloroethylene (13.9 mL, 17.3 g, 180 mmol) were dissolved in acetonitrile (300 mL) and irradiated with a 400 watt high pressure mercury lamp at room temperature under nitrogen atmosphere for 7 days. Then, all volatiles in the reaction mixture were removed by rotary evaporation. Subsequently, the crude product, acetic anhydride (85 mL) and zinc powder (100 g) were dissolved in toluene (120 mL) and stirred at 85 °C under nitrogen atmosphere for 72 h. After cooling to room temperature, the reaction was filtered to remove solid impurities and the residue was washed with toluene (50 mL x 4). The volatiles were removed by evaporation under vacuum. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 10: 1) and then recrystallized in n-hexane to give a white solid (8.1 g, 32%). The proton nuclear magnetic resonance spectrum (1H NMR, CDC13) of the prepared monomer is shown in Figure 1 Figure 1 which shows that succinimidyl cyclobutene monomer is successfully prepared by the preparation method of Example 1.

[0072] Example 2: Photoinitiated RAFT radical copolymerization of methyl acrylate and succinimidyl cyclobutene

[0073]

[0074] Methyl acrylate (9 mmol, 775 mg), succinimidyl cyclobutene (1 mmol, 213.2 mg), 2-[dodecylsulfanyl(thiocarbonyl)thio]-2-methylpropanoic acid (0.01 mmol, 3.7 mg) and dimethyl sulfoxide (5 mL) were charged into a 10 mL glass vial and sealed under nitrogen atmosphere. The glass vial was then irradiated with blue light (λ max = 455 nm, 10 W / cm -2 ) at room temperature. After the reaction was completed, the crude mixture was diluted with dichloromethane and precipitated into excess cold methanol, followed by centrifugal separation. The main chain containing succinimidyl cyclobutane poly(methyl acrylate) (m = 99, n = 800, k = 1) was produced with a specific number average molecular weight (75.8 kg / mol) and a molecular weight distribution (1.19). The proton nuclear magnetic resonance spectrum (1H NMR, CDC13) of the prepared copolymer product is shown in Figure 1 Figure 2 ​​As shown in the figure, it can be clearly seen that each functional group in the copolymer corresponds to the proton NMR spectrum, indicating that the preparation method of Example 2 successfully prepared polymethyl acrylate with succinimide cyclobutane in the main chain.

[0075] Example 3: Photo-initiated RAFT radical copolymerization of N,N-dimethylacrylamide and succinimide cyclobutene

[0076]

[0077] Under a nitrogen atmosphere, N,N-dimethylacrylamide (9 mmol, 892 mg), succinimide cyclobutene (1 mmol, 213.2 mg), 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid (0.01 mmol, 3.7 mg), and dimethyl sulfoxide (5 mL) were placed into a 10 mL glass bottle and sealed. The bottle was then placed under blue light (λ) at room temperature. max =455nm, 10W / cm -2 The reaction was carried out under irradiation. After the reaction, the crude mixture was diluted with dichloromethane and precipitated in excess cold methanol, and then centrifuged. Poly(N,N-dimethylacrylamide) (m=50, n=2000, k=2) with a main chain containing succinimide cyclobutane and a specific number-average molecular weight (176.9 kg / mol) and molecular weight distribution (1.15) was generated. The proton NMR spectrum of the prepared copolymer was... 1 H NMR (CDCl3) figure as shown Figure 3 As shown in the figure, it can be clearly seen from the figure that each functional group in the copolymer corresponds to the proton spectrum, indicating that the preparation method of Example 3 was successfully used to prepare polyN,N-dimethylacrylamide with succinimide cyclobutane in the main chain.

[0078] The difference between Example 3 and Example 2 is as follows:

[0079] The vinyl monomers were expanded from acrylates to acrylamides, thus demonstrating that the cyclobutene monomer of formula (II) has good copolymerization activity with different vinyl monomers, thereby obtaining the target vinyl polymer.

[0080] Example 4: Polymer ultrasonic activation experiment

[0081]

[0082] In each experiment, a 50 mL glass container containing a THF solution (2 mg / mL) of the polymer from Example 2 was ultrasonically treated with a pulse sequence of 1 second on, 1 second off (vibration frequency 20 kHz), and the temperature was maintained at 0 °C for a total duration of 24 h to obtain activated polymethyl acrylate. The 1H NMR spectrum of the activated polymethyl acrylate was then analyzed. 1H NMR, CDC13) chart as shown in Figure 1. From the chart, it can be clearly seen that each functional group in the copolymer corresponds to the hydrogen spectrum, indicating that the polyacrylate containing imide groups in the main chain is successfully prepared by the preparation method of Example 4. Figure 4

[0083] Example 5: Polymer degradation experiment

[0084]

[0085] After ultrasonic treatment, the solvent was removed by rotary evaporation under reduced pressure, and 10 mg of the polymer in Example 4 was dissolved in 5 mL (10 / 1, v / v, pH = 5) trifluoroacetic acid / water, and stirred at 40°C for 24 h. After the reaction was completed, the volatile matter was removed by rotary evaporation and dried. The gel permeation chromatogram of the hydrolysis product is shown in Figure 2, and the molecular weight of the polymer is 4.7 kg / mol, and the molecular weight distribution is 3.59, indicating that the degradation of the polyacrylate is successfully achieved by the method of Example 5. Figure 5

[0086] Example 6

[0087]

[0088] In each experiment, the THF solution (2 mg / mL) containing the polymer in Example 3 in a 50 mL glass container was subjected to ultrasonic treatment, and the pulse sequence was 1 second on and 1 second off (vibration frequency was 30 kHz), and the temperature was maintained at 50°C. After a total of 72 h, the activated poly N,N-dimethylacrylamide nuclear magnetic resonance hydrogen spectrum ( 1 H NMR, CDC13) chart as shown in Figure 1. From the chart, it can be clearly seen that each functional group in the copolymer corresponds to the hydrogen spectrum, indicating that the polyacrylate containing imide groups in the main chain is successfully prepared by the preparation method of Example 4.

[0089] Example 6 extends the vinyl polymer from the acrylate polymer to the acrylamide polymer, indicating that the vinyl polymer of different structures of formula (a) can achieve ring opening reaction of cyclobutane under the action of mechanical force, thereby obtaining activated poly N,N-dimethylacrylamide.

[0090] Example 7

[0091]

[0092] ​​After the ultrasonic treatment, the solvent was removed by rotary evaporation under reduced pressure. 10 mg of the polymer from Example 6 was dissolved in 5 mL of an aqueous hydrogen chloride solution (pH = 1) and stirred at 40 °C for 12 h. After the reaction was completed, the volatiles were removed by rotary evaporation and dried. The gel permeation chromatogram showed that the molecular weight of the polymer was 5.1 kg / mol and the molecular weight distribution was 2.3, indicating that the degradation of poly N,N-dimethylacrylamide (m = 50, n = 2000, k = 2, p = 50) was successfully achieved using the method of this Example 7.

[0093] Example 7 expands the scope of the activated vinyl polymer from acrylate-based polymers to acrylamide-based polymers, and after the acrylamide-based polymer is activated, chemical degradation can be achieved with the addition of a specific hydrolysis reaction.

[0094] Example 8

[0095]

[0096] In each experiment, a 50 mL glass container containing a THF solution (2 mg / mL) of the above-structured polymer was subjected to ultrasonic treatment, with a pulse sequence of 1 second on and 1 second off (vibration frequency of 15 kHz), and the temperature was maintained at 100 °C. After a total of 12 h, the activated poly(methyl acrylate) was obtained, and the proton nuclear magnetic resonance spectrum ( 1 HNMR, CDC13) showed that each functional group corresponded to the hydrogen spectrum, indicating that the activated poly(methyl acrylate) (m = 20, n = 100, k = 2) was obtained.

[0097] Example 8 is based on an acrylamide-based polymer as the basic backbone, and the ring-opening reaction of cyclobutane is achieved under mechanical force, thereby expanding the cleavable functional group from the imide structure in Example 4 to the ester group, thereby obtaining activated vinyl polymers of different structures.

[0098] Example 9

[0099]

[0100] After the ultrasonic treatment, the solvent was removed by rotary evaporation under reduced pressure. 10 mg of the polymer from Example 8 was dissolved in 5 mL of an aqueous acetic acid solution (pH = 3) and stirred at 40 °C for 36 h. After the reaction was completed, the volatiles were removed by rotary evaporation and dried. The gel permeation chromatogram showed that the molecular weight of the polymer was 2.0 kg / mol and the molecular weight distribution was 1.9, indicating that the degradation of poly(methyl acrylate) (m = 20, n = 100, k = 2, p = 25) was successfully achieved using the method of this Example 9.

[0101] The hydrolysis of the imide in Example 5 results in an oligomer with an amide bond or a carboxylic acid at the end. The hydrolysis reaction of the ester bond in Example 9 can result in an oligomer with a carboxylic acid and a hydroxyl group at the end, thereby enabling chemical degradation and further expanding the diversity of degradation using the hydrolysis reaction.

[0102] Example 10

[0103]

[0104] In each experiment, a 50 mL glass container containing a THF solution (2 mg / mL) of the above-structured polymer was subjected to ultrasonic treatment with a pulse sequence of 1 second on and 1 second off (vibration frequency of 50 kHz) at a temperature of 120°C. After a total duration of 6 h, an activated polystyrene was obtained, and the 1H NMR spectrum of the activated polystyrene is shown in FIG. 1. 1 The H NMR spectrum of the activated polystyrene is shown in FIG. 1, and the functional groups in the spectrum correspond to the hydrogen spectrum, indicating that the activated polystyrene (m = 500, n = 50, k = 1) was obtained.

[0105] Example 10 is based on polystyrene as the basic skeleton, and the ring-opening reaction of cyclobutane is achieved under mechanical force, thereby expanding the cleavable functional group from the imide structure in Example 4 to an ester group, thereby obtaining activated polystyrene with different structures.

[0106] Example 11

[0107]

[0108] After ultrasonic treatment, the solvent was removed by rotary evaporation under reduced pressure, and 10 mg of the polymer in Example 10 was dissolved in 5 mL of trifluoroacetic acid / water (70 / 1 v / v, pH = 2) and stirred at 80°C for 36 h. After the reaction was completed, the volatile matter was removed by rotary evaporation and dried. The gel permeation chromatogram showed that the molecular weight of the polymer was 3.1 kg / mol, and the molecular weight distribution was 2.5, indicating that the degradation of polystyrene was successfully achieved using the method of this Example 11 (m = 500, n = 50, k = 1, p = 30).

[0109] Example 5 uses the hydrolysis of imide to degrade polymethyl acrylate, and Example 11 obtains polystyrene oligomers with carboxylic acid and hydroxyl groups at the end, further expanding the universality of vinyl polymers.

[0110] The above describes exemplary embodiments of the present application. However, the scope of protection of the present application is not limited to the above-described embodiments. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for the controlled degradation of a vinyl polymer, characterized in that, Comprising: (S1) performing ring-opening reaction of a vinyl polymer represented by formula a under mechanical force stimulation to obtain an activated vinyl polymer represented by formula b; (S2) hydrolyzing the activated vinyl polymer represented by formula b in step (S1) in an acidic environment to realize degradation of the vinyl polymer; In formula a and formula b, R1, R2and R3are the same or different, and are independently selected from H, C 1-20 alkyl; R4, R5and R6are identical or different, independently of each other selected from the group consisting of H, -C(=0)OC 1-20 alkyl, -C 0-6 alkylene-C 6-20 aryl, halogen, -COOH, -C(=0)NR 11 R 12 , -CN, -0(0=)CC 1-20 alkyl; R7is R a substituted heteroatom E, wherein the heteroatom E is selected from boron, nitrogen, silicon, phosphorus atom; or R7is a heteroatom B, the heteroatom B is oxygen or sulfur; ring A is further substituted with one or more R a selected from H, -C 1-20 alkyl, -C(=O)OC 1-20 alkyl, -C 0-6 alkylene-C 6-20 aryl, halogen, -COOH, -C(=O)NR 11 R 12 , -CN, -O(O=)CC 1-20 alkyl, R8is carbonyl or thiocarbonyl; R 11 and R 12 are independently from each other selected from H, C 1-12 alkyl; wherein 1≤m:k≤500; 20≤m≤1000; 20≤n≤2000.

2. The method of claim 1, wherein, In step (S1), the method of applying mechanical force includes at least one of ultrasonic method and ball milling method. Preferably, the time of mechanical force stimulation is 30s-72h. Preferably, the vibration frequency of mechanical force is 5-50kHz. Preferably, in step (S1), a vinyl polymer solution represented by formula a is used for mechanical force stimulation. Preferably, the concentration of the vinyl polymer solution represented by formula a is 0.01-50mg / mL. Preferably, in step (S1), the temperature of ring-opening reaction is 0-120℃.

3. The method according to claim 1 or 2, characterized in that, In step (S2), the pH of the acidic environment is <7, the temperature of hydrolysis is 0-250℃; the time of hydrolysis is 6-48h.

4. The method according to any one of claims 1 to 3, characterized in that, R1, R2and R3are identical or different, independently of each other selected from the group consisting of H, C 1-12 alkyl; also preferably H, C 1-6 alkyl.

5. The method according to any one of claims 1 to 4, characterized in that, R4, R5and R6are identical or different and independently of each other selected from the group consisting of H, -C(=0)OC 1-12 alkyl, -C 0-6 alkylene-C 6-14 aryl, halogen, -COOH, -CONR 11 R 12 , -CN, -O(O=)CC 1-12 alkyl; further preferred H, -C(=0)OC 1-6 alkyl, -C 0-6 alkylene-C 6-14 aryl, halogen, -COOH, -CONR 11 R 12 , -CN, -O(O=)CC 1-6 alkyl; Preferably, R 11 and R 12 are independently of each other selected from H, C 1-6 alkyl. Preferably, the heteroatom E is nitrogen; preferably, the heteroatom B is preferably oxygen.

6. The method according to any one of claims 1 to 5, characterized in that, 10≤m:k≤500. Preferably, 20≤m≤500. Preferably, 50≤n≤2000. Preferably, 1≤p≤60.

7. The method according to any one of claims 1 to 4, characterized in that, The preparation method of the vinyl polymer represented by formula a specifically comprises the following steps: (1) mixing a vinyl monomer represented by formula I, a cyclobutenyl monomer represented by formula II, a RAFT agent represented by formula III and an organic solvent under anhydrous and oxygen-isolated conditions to form a pre-reaction mixture; (2) placing the pre-reaction mixture of step (1) under a light source with a predetermined wavelength and light intensity to prepare a vinyl polymer represented by formula a; wherein R1, R2, R3, R4, R5, R6, R7, A have the meanings as described above; R8is selected from the group consisting of substituted or unsubstituted C 1-20 alkyl, substituted or unsubstituted C 0-6 alkylene-C 6-20 aryl, substituted by R c halogen, -COOH, -CN, -N-(C(O)-R 13 )2, -C(=O)NR 14 R 15 ; R 13 , R 14 and R 15 are identical or different and independently from each other selected from the group consisting of H, C 1-12 alkyl; R9is substituted or unsubstituted C 1-20 alkyl, substituted or unsubstituted C 0-6 alkylene-C 6-20 aryl, substituted or unsubstituted -S-C 1-20 alkyl, substituted or unsubstituted -O-C 1-20 alkyl, substituted or unsubstituted -NH-C 1-20 alkyl; wherein the substituents R b are -N-(C(O)-R 13 ), -C(=O)NR 14 R 15 , -C(O)OC 1-12 alkyl, -C 1-12 alkyl-COOH after dehydration of the acid anhydride, -OC 1-12 alkyl, -COOH; R 13 , R 14 and R 15 are identical or different, independently of each other, selected from H, C 1-12 alkyl.

8. The method of claim 7, wherein, The organic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, dichloromethane, 1,2-dichloroethane, chloroform, acetone, ethyl acetate, benzene, toluene, tetrahydrofuran, diethyl ether, acetonitrile, 1,4-dioxane.

9. The method of claim 7, wherein, The molar ratio of the vinyl monomer: the cyclobutenyl monomer: the RAFT agent is (10-10000):(10-10000):

1. Preferably, the concentration of the RAFT agent in the organic solvent is 0.00001-10mol / L.

10. The method of claim 7, wherein, In step (2), the light source has a light intensity of not less than 0.1 W / cm -2 , preferably 1-20 W / cm -2 ; and a wavelength range of 200-700 nm.

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