Method for preparing block polymer by light-induced recoverable macromolecules

Abstract

The invention discloses a method for preparing a block polymer by light-induced recyclable macromolecules, which comprises the following steps: S1, mixing an imide compound, a first monomer and a nitrogen-containing initiator, and generating a first block polymer under an illumination condition; and S2, mixing the first block polymer with a second monomer and an imide compound again, and continuously reacting under an illumination condition to form a diblock polymer, namely a final block polymerization product. According to the method disclosed by the invention, a light source and illumination time with proper parameters can be selected as required, the reaction progress is convenient to control under illumination conditions, and the problem that the reaction progress is uncontrollable due to temperature change in thermal initiation polymerization does not exist; meanwhile, the photo-initiation polymerization reaction is rapid and faster than thermal initiation polymerization; the reaction conditions are simple, the operation is simple and convenient, and the industrial application potential is realized.

Description

Technical Field

[0001] The invention relates to the fields of light induction and polymer materials, and in particular to a method for preparing block polymers from light-induced recyclable polymers. Background Art

[0002] Due to their unique microphase separation characteristics, excellent mechanical properties, and chemical stability, block polymers have a wide range of applications in polymer materials, drug delivery, coatings, nanotechnology, and energy storage. Currently, the preparation of block polymers generally relies on living polymerization techniques such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), and reversible terminator-mediated polymerization (RDRP). These methods use controlled free radical or ionic polymerization to keep the polymer chain active under appropriate conditions, allowing monomers to be introduced at different stages to achieve block copolymerization.

[0003] Although these methods have made significant progress in the preparation of block polymers, they still have some limitations. For example, ATRP polymerization usually requires a metal catalyst (such as CuBr), and the residual metal may affect the application of the polymer, especially in the field of biomedical materials. In addition, the ATRP reaction requires a strict oxygen-free environment to prevent free radicals from terminating the reaction, which increases the complexity of the operation. Although RAFT polymerization can be carried out under relatively mild conditions, it usually requires specific chain transfer agents and has a long reaction time, which affects the efficiency of industrial applications. In addition, these methods have certain challenges in the recovery and reuse of polymers after use, which limits the sustainability of the materials.

[0004] In recent years, photoinitiated polymerization has gained increasing attention due to its advantages, including mild reaction conditions, spatiotemporal controllability, and lack of metal contamination. Some studies have explored methods for photoinitiated block polymerization, but these still require additional processing steps, such as post-treatment to remove the photoinitiator, a strictly oxygen-free environment, or additional catalyst systems. Furthermore, most photoinitiated methods struggle to achieve reversible recovery and recycling of polymers, thus leaving room for improvement in the field of sustainable polymer materials.

[0005] Therefore, developing a method that can rapidly synthesize block polymers through photoinitiation at room temperature and in an air environment, while making the polymers recyclable and reusable, has important research value and application prospects. Summary of the Invention

[0006] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and provide a method for producing block polymers from light-induced recyclable polymers. This method does not require inert gas protection or metal catalysts, and can achieve polymer repolymerization, providing a new strategy for the preparation of block polymers that is efficient, environmentally friendly and sustainable.

[0007] The technical solution adopted by the present invention is as follows: A method for producing a block polymer by light-induced recyclable polymer comprises the following steps:

[0008] S1, mixing an imide compound, a first monomer and a nitrogen-containing initiator, and generating a first block polymer under light conditions;

[0009] S2, mixing the first block polymer with the second monomer and the imide compound again, and continuing the reaction under light conditions to form a diblock polymer, that is, obtaining a final blocked polymer product;

[0010] The first monomer and the second monomer are the same or different acrylate monomers.

[0011] In the present invention, if the acrylate monomer is liquid, the imide, nitrogen-containing initiator, and acrylate monomer can be directly mixed according to a proportion; if the acrylate monomer is solid, the imide, nitrogen-containing initiator, and acrylate monomer can be mixed and dissolved in an organic solvent, such as dimethyl sulfoxide (DMSO), according to a proportion.

[0012] like Figure 1 As shown, the imide compound and nitrogen-containing initiator of the present invention form a charge transfer complex under light conditions. This charge transfer complex can dissociate to generate free radicals formed by the nitrogen-containing initiator. The nitrogen-containing initiator free radicals then initiate polymerization of the first monomer (acrylate monomer) to produce a first-stage polymer. The first-stage polymer is then added with the imide compound and a second monomer (acrylate monomer, which may have the same or different acrylate monomer structure as the first monomer) and exposed to light. The reaction continues under light conditions, and the residual initiation site at the end of the first block initiates polymerization of the second monomer, forming a copolymer having a block structure.

[0013] Preferably, the imide compound is one of the following structures:

[0014]

[0015] wherein R1 is independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, methoxy, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl, halogen-substituted or unsubstituted linear or branched alkyl of 1 to 10 carbon atoms, and any of the above compounds already having such a branch;

[0016] R2 to R5 are independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, and methoxy;

[0017] R6, R 13 、R16 、R 19 、R 24 Independently selected from hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, methoxy, nitro, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl, halogen-substituted or unsubstituted straight-chain or branched alkyl of 1 to 10 carbon atoms, and any of the above compounds already having such a branch;

[0018] R7~R 12 、R 14 、R 15 、R 17 、R 18 、R 20 ~R 23 、R 25 ~R 28 Independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, methoxy and nitro.

[0019] Preferably, R1 is selected from methyl, phenyl, methoxy or benzyl; R2 to R5 are independently selected from hydrogen, halogen, methoxy or dimethylamino; R6 is selected from methyl, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl; R7 to R 12 R is independently selected from hydrogen, halogen, nitro, methoxy or dimethylamino. 13 、R 16 R is selected from methyl, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl, halogen-substituted or unsubstituted straight-chain or branched alkyl of 1 to 10 carbon atoms; 14 、R 15 、R 17 、R 18 R is independently selected from hydrogen or halogen. 19 、R 24 R is selected from methyl, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl, halogen-substituted or unsubstituted straight-chain or branched alkyl of 1 to 10 carbon atoms; 20 ~R 23 、R 25 ~R 28 are independently selected from hydrogen, halogen, cyano or methoxy. 12 、R 13 、R 16 、R 14 、R 15 、R 17 、R 18 、R 19 、R 24 、R 20 ~R 23 、R 25~R 28 The preferred structure has low toxicity and can effectively improve the conversion rate of the polyacrylamide compound by regulating the wavelength and time of illumination.

[0020] Preferably, the imide compound is one of the following structures:

[0021]

[0022]

[0023]

[0024] Preferably, the structure of the nitrogen-containing initiator is:

[0025]

[0026] Among them, R 29 ~R 31 Independently selected from a linear or branched alkyl group having 1 to 10 carbon atoms, a methyl group, a halogen group, a cyano group, a mercapto group, a phenyl group, a piperazinyl group, a phenothiazinyl group, or a linear or branched alkyl group having 1 to 10 carbon atoms with the above substituents.

[0027] Preferably, the structure of the nitrogen-containing initiator is selected from one of the following structures:

[0028]

[0029] Preferably, the structure of the acrylic ester monomer is:

[0030]

[0031] where R 32 represents hydrogen or methyl;

[0032] R 33 Independently selected from hydrogen, methyl, straight-chain or branched alkyl or alkyl alcohol having 1 to 10 carbon atoms, hydroxyl, carboxyl, cyano, mercapto, amide, vinyl, alkoxy, alkylthio, nitro, piperazinyl, phenothiazinyl, optionally substituted or unsubstituted phenyl, and straight-chain or branched alkyl chains having 1 to 10 carbon atoms with the above substituents.

[0033] Preferably, the acrylic acid ester monomer is selected from one of the following structures:

[0034]

[0035] More preferably, the illumination condition is ultraviolet light or visible light with a wavelength of 280nm to 600nm, and the illumination time is 1s to 5h.

[0036] More preferably, the molar ratio of the nitrogen-containing initiator to the acrylate monomer is 1:(1-1000); and the molar ratio of the imide compound to the acrylate monomer is 1:(1-1000).

[0037] More preferably, the process further includes a polymer purification step: dissolving the first block polymer in S1 or the diblock polymer in S2 in dichloromethane to obtain a mixture solution; then dripping the mixture solution into anhydrous petroleum ether, repeatedly filtering, and drying to obtain a purified polymer product. Purification can remove acrylate free radicals, nitrogen-containing initiators, and imide compounds from the reaction mixture, thereby obtaining a pure polyacrylate compound.

[0038] The present invention also provides a block polymer prepared by the above method. The number average molecular weight of the first block polymer can reach more than 10,000, and the weight average molecular weight can reach more than 50,000; the number average molecular weight of the diblock polymer can reach more than 30,000, and the weight average molecular weight can reach more than 100,000.

[0039] The beneficial effects of the present invention are:

[0040] (1) The imide compound and the nitrogen-containing initiator in the present invention form a charge transfer complex under light conditions. This charge transfer complex can dissociate to generate free radicals formed by the nitrogen-containing initiator. The nitrogen-containing initiator free radicals then initiate polymerization of the acrylate monomer to obtain a first-stage polymer. The imide compound and the second monomer are then added to the first-stage polymer to produce a block polymer. The method for preparing block polymers from light-induced recyclable polymers proposed in the present invention has simple reaction conditions, is easy to operate, and has potential for industrial application.

[0041] (2) The method for producing block polymers from recyclable polymers of the present invention can select appropriate light source parameters and illumination time as needed. The illumination conditions facilitate control of the reaction progress, and the problem of uncontrollable reaction progress caused by temperature changes in thermally initiated polymerization does not exist. At the same time, light-induced polymerization reacts rapidly, faster than thermally initiated polymerization. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the principle of preparing block polymers according to the present invention;

[0043] Figure 2 is a hydrogen spectrum of the reaction system of the present invention in CDCl3 before illumination;

[0044] Figure 3 is the hydrogen spectrum of the reaction system polymer prepared in Example 1 in CDCl3;

[0045] Figure 4is the GPC spectrum of the purified polymer prepared in Example 1 (THF is the mobile phase);

[0046] Figure 5 is the hydrogen spectrum of the reaction system polymer prepared in Example 2 in CDCl3;

[0047] Figure 6 is the GPC spectrum of the purified polymer prepared in Example 2 (THF is the mobile phase);

[0048] Figure 7 is the hydrogen spectrum of the reaction system polymer prepared in Example 3 in CDCl3;

[0049] Figure 8 is the GPC spectrum of the purified polymer prepared in Example 3 (THF is the mobile phase);

[0050] Figure 9 is the hydrogen spectrum of the reaction system polymer prepared in Example 4 in CDCl3;

[0051] Figure 10 This is the GPC spectrum of the purified polymer prepared in Example 4 (THF is the mobile phase). DETAILED DESCRIPTION

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] 1. Mix an imide compound with structure B1, a nitrogen-containing initiator with structure E14, and an acrylate monomer with structure F2 in a ratio of 1:1:200. Irradiate the mixture for 30 minutes under a 365 nm wavelength, 10 W power light source to complete the polymerization reaction and obtain a mixture. Dissolve the mixture in dichloromethane and then add it dropwise into anhydrous petroleum ether to produce a precipitate. Filter and clean the solution, then dry it to obtain a purified first-stage acrylate polymer compound.

[0055]

[0056] 2. The first block polymer (0.5 g) was mixed again with monomer F1 (1.5 ml) and imide compound B1 (0.01 g). The mixture was irradiated for 2 hours under a 365 nm wavelength, 10 W power light source to complete the polymerization reaction and obtain a mixture. The mixture was dissolved in dichloromethane solution and then dripped into anhydrous petroleum ether to produce a precipitate. The solution was then filtered and washed, and then dried to obtain a purified diblock polymer, i.e., the final block polymer product.

[0057]

[0058] Figure 2 This is the hydrogen spectrum of the system in CDCl3 before the reaction.

[0059] analyze Figure 2 It can be seen that when the imide compound with structure B1 is mixed with the nitrogen-containing initiator with structure E14 and the acrylate monomer with structure F2, the hydrogen spectrum before the polymerization reaction is initiated by light shows characteristic peaks for each component. The characteristic peaks of the imide compound with structure B1 are labeled a, b, c, d, e, f, and g, and the characteristic peaks of the nitrogen-containing initiator with structure E14 are labeled 1, 2, and 3. The characteristic peaks of the acrylate monomer with structure F1 are labeled A, B, C, D, and E.

[0060] Then the second stage polymerization is initiated again. In this embodiment, the second stage polymerization monomer is also bulk polymerized; Figure 3 The hydrogen spectra of the first and final block polymerization products obtained in this example in CDCl3 are shown in Figure 2. It can be observed that the peak of the product after the second polymerization is the sum of the two homopolymer NMR peaks.

[0061] Figure 4 GPC spectra (THF as the mobile phase) of the first-stage polymer and the final block product obtained after purification. The first-stage polymer has a number-average molecular weight (Mn) of 44,017, a weight-average molecular weight (Mw) of 108,467, and a PDI of 2.46. The block polymer has a number-average molecular weight (Mn) of 105,669, a weight-average molecular weight (Mw) of 352,700, and a PDI of 3.33.

[0062] Example 2

[0063] 1. Mix the imide compound (B1), the nitrogen-containing initiator (E4), and the acrylate monomer (F2) in a ratio of 1:1:200. Irradiate the mixture for 30 minutes under a 365nm wavelength, 10W power light source to complete the polymerization reaction and obtain a mixture. Purify the mixture by dissolving it in dichloromethane and then adding it dropwise to anhydrous petroleum ether to produce a precipitate. Filter and clean the solution, then dry it to obtain the purified first-stage acrylate polymer compound.

[0064]

[0065] 2. The first block polymer (0.5 g) was mixed again with monomer F9 (1.5 ml) and imide compound B1 (0.01 g). The mixture was irradiated for 2 h under a 365 nm wavelength, 10 W power light source to complete the polymerization reaction. Post-polymerization purification methods were the same as those in step 1.

[0066]

[0067] Figure 5 : This is the hydrogen spectrum of the first stage polymer and the block polymer prepared in this example in CDCl3.

[0068] Figure 6 This is the GPC spectrum (THF as the mobile phase) of the first-stage polymer and block polymer obtained after purification in this example. The first-stage polymer has a number-average molecular weight (Mn) of 36,709, a weight-average molecular weight (Mw) of 104,154, and a PDI of 2.83. The block polymer has a number-average molecular weight (Mn) of 242,690, a weight-average molecular weight (Mw) of 789,241, and a PDI of 3.25.

[0069] Example 3

[0070] 1. Mix the imide compound (B7), the nitrogen-containing initiator (E2), and the acrylate monomer (F1) in a ratio of 1:1:200. Irradiate the mixture for 30 minutes under a 365 nm wavelength, 10 W power light source to complete the polymerization reaction and obtain a mixture. Purify the mixture by dissolving it in dichloromethane and then adding it dropwise to anhydrous petroleum ether to produce a precipitate. Filter and clean the solution, then dry it to obtain the purified first-stage acrylate polymer compound.

[0071]

[0072] 2. The first block polymer (0.5 g) was mixed again with monomer F2 (1.5 ml) and imide compound B7 (0.01 g). The mixture was irradiated under a 365 nm wavelength, 10 W power light source for 2 h to complete the polymerization reaction. Post-polymerization purification methods were the same as those in step 1.

[0073]

[0074] Figure 7 This is the hydrogen spectrum of the polymer prepared in this example in CDCl3.

[0075] Figure 8 This is the GPC spectrum (THF as the mobile phase) of the first-stage polymer and block polymer obtained after purification in this example. The first-stage polymer has a number-average molecular weight (Mn) of 20,651, a weight-average molecular weight (Mw) of 96,466, and a PDI of 4.67. The block polymer has a number-average molecular weight (Mn) of 60,267, a weight-average molecular weight (Mw) of 308,308, and a PDI of 5.11.

[0076] Example 4

[0077] 1. Mix an imide compound with a C7 structure, a nitrogen-containing initiator with a E10 structure, and an acrylate monomer with a F2 structure in a ratio of 1:1:200. Irradiate the mixture for 30 minutes under a 365nm wavelength, 10W power light source to complete the polymerization reaction and obtain a mixture. Purify the mixture by dissolving it in dichloromethane solution and then adding it dropwise into anhydrous petroleum ether to produce a precipitate. Filter and clean the solution, then dry it to obtain the purified first-stage acrylate polymer compound.

[0078]

[0079] The first block polymer (0.5 g) was mixed again with monomer F1 (1.5 ml) and imide compound C7 (0.01 g) and irradiated for 2 h under a light source with a wavelength of 365 nm and a power of 10 W to complete the polymerization reaction. The post-polymerization purification method was the same as the purification method in step 1.

[0080]

[0081] Figure 9 This is the hydrogen spectrum of the polymer prepared in this example in CDCl3.

[0082] Figure 10 This is the GPC spectrum (THF as the mobile phase) of the first-stage polymer and block polymer obtained after purification in this example. The first-stage polymer has a number-average molecular weight (Mn) of 44,136, a weight-average molecular weight (Mw) of 141,657, and a PDI of 3.20. The block polymer has a number-average molecular weight (Mn) of 158,788, a weight-average molecular weight (Mw) of 547,289, and a PDI of 3.44.

[0083] The description and drawings of the present invention are considered to be illustrative rather than restrictive. On the basis of the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features according to the disclosed technical content without creative work, and all of them are within the scope of protection of the present invention.

Claims

1. A method for producing block polymers from light-induced recyclable polymers, characterized in that: The following steps are involved: S1, mixing an imide compound, a first monomer and a nitrogen-containing initiator, and generating a first block polymer under light conditions; S2, mixing the first block polymer with the second monomer and the imide compound again, and continuing the reaction under light conditions to form a diblock polymer, that is, obtaining a final blocked polymer product; The first monomer and the second monomer are the same or different acrylate monomers.

2. The method according to claim 1, characterized in that The imide compound is one of the following structures: wherein R1 is independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, methoxy, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl, halogen-substituted or unsubstituted linear or branched alkyl of 1 to 10 carbon atoms, and any of the above compounds already having such a branch; R2 to R5 are independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, and methoxy; R6, R 13 、R 16 、R 19 、R 24 Independently selected from hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, methoxy, nitro, optionally substituted or unsubstituted phenyl, optionally substituted or unsubstituted benzyl, halogen-substituted or unsubstituted straight-chain or branched alkyl of 1 to 10 carbon atoms, and any of the above compounds already having such a branch; R7~R 12 、R 14 、R 15 、R 17 、R 18 、R 20 ~R 23 、R 25 ~R 28 Independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, methoxy and nitro.

3. The method according to claim 2, characterized in that The imide compound is one of the following structures:

4. The method according to claim 1, wherein The structure of the nitrogen-containing initiator is: Among them, R 29 ~R 31 Independently selected from a linear or branched alkyl group having 1 to 10 carbon atoms, a methyl group, a halogen group, a cyano group, a mercapto group, a phenyl group, a piperazinyl group, a phenothiazinyl group, or a linear or branched alkyl group having 1 to 10 carbon atoms with the above substituents.

5. The method according to claim 4, characterized in that The structure of the nitrogen-containing initiator is selected from one of the following structures:

6. The method according to claim 1, wherein The structure of the acrylic acid ester monomer is: where R 32 represents hydrogen or methyl; R 33 Independently selected from hydrogen, methyl, straight-chain or branched alkyl or alkyl alcohol having 1 to 10 carbon atoms, hydroxyl, carboxyl, cyano, mercapto, amide, vinyl, alkoxy, alkylthio, nitro, piperazinyl, phenothiazinyl, optionally substituted or unsubstituted phenyl, and straight-chain or branched alkyl chains having 1 to 10 carbon atoms with the above substituents.

7. The method according to claim 6, characterized in that The acrylic acid ester monomer is selected from one of the following structures:

8. The method according to claim 1, characterized in that The illumination conditions are ultraviolet light or visible light with a wavelength of 280nm to 600nm, and the illumination time is 1s to 5h; the molar ratio of the nitrogen-containing initiator to the acrylate monomer is 1:(1 to 1000); the molar ratio of the imide compound to the acrylate monomer is 1:(1 to 1000).

9. The method according to claim 1, characterized in that The method further includes a polymer purification step: dissolving the first block polymer in S1 or the diblock polymer in S2 with dichloromethane to obtain a mixture solution; then dripping the mixture solution into anhydrous petroleum ether, repeatedly filtering, and drying to obtain a purified polymer product.

10. The block polymer prepared by the method according to any one of claims 1 to 9, characterized in that: The number average molecular weight of the first block polymer can reach more than 10,000, and the weight average molecular weight can reach more than 50,000; the number average molecular weight of the diblock polymer can reach more than 30,000, and the weight average molecular weight can reach more than 100,000.

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