Preparation method of grafted polymer brush copolymer

Abstract

The invention discloses a preparation method of a grafted polymer brush copolymer, which comprises the following steps: S1, mixing a styrene monomer, N-4-vinyl phenyl-N, N-dimethylamine, toluene and AIBN, heating, and reacting to generate a first section of polymer; and S2, mixing the first-section polymer with an acrylate monomer and an imide compound, and continuously reacting under an illumination condition to obtain the polymer brush copolymer. AIBN can be decomposed at high temperature to generate free radicals, polystyrene monomers are initiated to polymerize, and a first-section polymer is formed. The imide compound and a nitrogen-containing initiation site form a charge transfer complex under an illumination condition. The charge transfer complex can be dissociated to generate free radicals formed by nitrogen-containing initiation sites, and then the free radicals formed by the nitrogen-containing initiation sites initiate polymerization of acrylate monomers to obtain a grafted polymer brush copolymer. The preparation method is simple in reaction condition, simple and convenient to operate and suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention relates to the fields of light induction and polymer materials, and in particular to a method for grafting another polymer onto an existing polymer main chain. Background Art

[0002] Polymer materials have a wide range of applications in modern industry and scientific research, with block copolymers attracting significant attention due to their unique phase separation behavior and multifunctional properties. Block copolymer preparation methods primarily include traditional techniques such as living radical polymerization (e.g., reversible addition-fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP), and reversible complexation polymerization (RDRP)) and anionic polymerization. However, these methods typically require a strict oxygen-free, water-free environment and may involve metal catalysts or complex synthesis steps, increasing production costs and operational difficulty.

[0003] Among them, ATRP, as a widely used method for synthesizing block copolymers, relies on the action of metal catalysts (such as CuBr, CuCl, etc.) and ligands to precisely control the polymerization process. Although ATRP can be used to prepare structurally controllable block copolymers, the problem of metal residues limits its use in certain applications, such as biomedical materials, electronic materials, and food packaging. In addition, ATRP reactions usually require a strict oxygen-free environment, otherwise the metal catalyst is easily deactivated, reducing the polymerization efficiency.

[0004] In recent years, photoinitiated polymerization technology has gradually become an important research direction in the field of polymer synthesis due to its mild reaction conditions and high spatial selectivity. Photoinitiated free radical polymerization (PFRP) has become a green synthesis strategy that has attracted much attention because it can be carried out efficiently at room temperature and reduces dependence on metal catalysts. However, existing photoinitiated polymerization methods are mostly used for monomer polymerization or simple grafting polymerization. There are still certain challenges in efficiently initiating the growth of the second block on the formed polymer backbone. For example, most photoinitiator systems require special photosensitizers or oxygen inhibition inhibitors to prevent quenching of free radicals by oxygen, and the reaction time of most systems is relatively long, which affects the efficiency.

[0005] Polymer brushes are a special type of grafted polymer in which polymer chains are densely fixed to the substrate surface or main chain skeleton through chemical bonds or physical effects to form a highly extended structure. This structure has important applications in functional coatings, anti-fouling materials, biocompatible materials, and smart responsive materials due to its high surface density and controllable surface chemical properties. At present, the preparation methods of polymer brushes mainly include surface-initiated atom transfer radical polymerization (SI-ATRP), reversible addition-fragmentation chain transfer polymerization (SI-RAFT), and surface photoinitiated polymerization. However, existing methods usually require strict reaction conditions, such as oxygen-free, water-free environment, as well as expensive metal catalysts or complex initiation systems.

[0006] Therefore, there is an urgent need for a simpler polymerization method to enable better industrial production of block polymers with various morphologies. Summary of the Invention

[0007] The present invention aims to address the aforementioned problems of the prior art by providing a method for preparing grafted polymer brush copolymers. The polymerization strategy of this invention offers a novel approach to the synthesis of block copolymers and polymer brushes, and is particularly suitable for applications sensitive to the polymerization environment, such as the development of biodegradable polymer materials, antifouling interfaces, smart responsive materials, and other high-performance functional polymers.

[0008] The technical solution adopted by the present invention is as follows: a method for preparing a grafted polymer brush copolymer, comprising the following steps:

[0009] S1. Styrene monomer, N-4-vinylphenyl-N,N-dimethylamine, toluene, and AIBN are mixed, heated, and reacted to form a first-stage polymer;

[0010] S2. Mixing the first-stage polymer with an acrylate monomer and an imide compound, and continuing the reaction under light conditions to obtain a polymer brush copolymer.

[0011] like Figure 1 As shown, in the present invention, AIBN decomposes at high temperature to generate free radicals, which initiate polymerization of polystyrene monomers to produce the first-stage polymer, which is a random copolymer of styrene and N-4-vinylphenyl-N,N-dimethylamine. Under light, the imide compound and the nitrogen-containing initiating sites form a charge transfer complex, which dissociates to generate free radicals formed from the nitrogen-containing initiating sites. These free radicals then initiate polymerization of the acrylate monomers to produce the grafted polymer brush copolymer.

[0012] Preferably, the imide compound is one of the following structures:

[0013]

[0014] 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;

[0015] R2 to R5 are independently selected from one of hydrogen, halogen, amino, hydroxyl, carboxyl, cyano, thiol, amide, and methoxy;

[0016] 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;

[0017] 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.

[0018] 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 ~R23 、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.

[0019] Preferably, the imide compound is one of the following structures:

[0020]

[0021]

[0022]

[0023] Preferably, the structure of the acrylic ester monomer is:

[0024] where R 29 represents hydrogen or methyl.

[0025] R 30 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.

[0026] Preferably, the acrylic acid ester monomer is selected from one of the following structures:

[0027]

[0028] Preferably, the heating temperature in S1 is 40° C.-100° C.; and the reaction time is 2 h-24 h.

[0029] More preferably, the illumination condition in S2 is ultraviolet light or visible light with a wavelength of 280 nm to 600 nm, and the illumination duration is 1 second to 5 hours. The illumination duration affects the molecular weight distribution of the prepared grafted polymer brush copolymer and the conversion rate of the acrylate monomer. The longer the illumination time, the higher the conversion rate of the acrylate monomer.

[0030] More preferably, the molar ratio of the imide compound to the acrylate monomer is 1:(1-1000).

[0031] More preferably, the process further includes a polymer purification step: dissolving the first-stage polymer in S1 or the high-molecular-weight brush copolymer 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.

[0032] The present invention also provides a block polymer prepared by the above preparation method, wherein 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 10,000; the number average molecular weight of the polymer brush copolymer can reach more than 20,000, and the weight average molecular weight can reach more than 100,000.

[0033] The beneficial effects of the present invention are:

[0034] (1) In the present invention, AIBN can decompose at high temperatures to generate free radicals, which initiate polymerization of polystyrene monomers to form a first-stage polymer. The first-stage polymer is mixed with an acrylate monomer and an imide compound, and the reaction continues under light conditions. The N,N-dimethylamine in the main chain of the first block polymer initiates polymerization of the second monomer, and a second polymer chain is grafted onto the main chain to prepare a polymer brush copolymer.

[0035] (2) The preparation method of the present invention has simple reaction conditions, is easy to operate, and can be industrialized for large-scale production.

[0036] (3) The present invention adopts a staged polymerization strategy to give full play to the synergistic advantages of thermal initiation and photoinitiation. In the first stage of polymer synthesis, the reaction temperature is controlled and a thermal initiator is used to ensure the stable progress of the free radical polymerization reaction; in the second stage of grafting, photoinitiated polymerization is innovatively used, and the grafting reaction can be controlled by regulating the wavelength, irradiation power and time of the light source. Compared with the traditional single thermal initiation system, this method solves the cumbersome problems of traditional polymerization grafting through photoinitiation. The photoinitiation stage has the outstanding advantages of short time, mild conditions and no thermal inertia effect, which improves the preparation efficiency of the copolymer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the principle of preparing block polymers from recyclable macromolecules disclosed in the present invention;

[0038] Figure 2 This is the hydrogen spectrum in CDCl3 of the first stage polymer prepared by the method of Example 1 herein;

[0039] Figure 3 is the hydrogen spectrum of the grafted polymer brush polymer, the first stage polymer, and the pure acrylate polymer prepared in Example 1 of the present disclosure in CDCl3;

[0040] Figure 4This is the GPC spectrum of the purified polymer prepared in Example 1 of the present disclosure (THF is the mobile phase).

[0041] Figure 5 This is the GPC spectrum of the purified polymer prepared in Example 2 of the present disclosure (THF is the mobile phase).

[0042] Figure 6 This is the hydrogen spectrum in CDCl3 of the first stage polymer prepared by the method of Example 3 herein.

[0043] Figure 7 This is the GPC spectrum of the purified polymer prepared in Example 3 of the present disclosure (THF is the mobile phase). DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0045] Example 1

[0046] Styrene monomer (10 ml of the following structure) and N-4-vinylphenyl-N,N-dimethylamine monomer were mixed in a ratio of 20:1. Then, 40 ml of toluene and 0.07 g of AIBN were added. The mixture was reacted at 85°C for 6 hours to obtain a mixture. The mixture was dissolved in dichloromethane and then added dropwise to anhydrous petroleum ether. The solution produced a precipitate, which was then filtered, cleaned, and dried to obtain the purified first-stage polystyrene polymer compound.

[0047]

[0048] The first-stage polymer (0.5 g) was mixed again with monomer E2 (1.5 ml) and imide compound B1 (0.01 g). The mixture was irradiated for 1 hour under a 365 nm wavelength, 10 W power light source to complete the polymerization reaction. The polymerization product was dissolved in dichloromethane and then back-dripped into anhydrous petroleum ether to produce a precipitate. The solution was then filtered, cleaned, and dried to obtain the purified graft polymer brush copolymer.

[0049]

[0050] Figure 2 This is the hydrogen spectrum of the first stage polymer prepared in this example in CDCl3.

[0051] analyze Figure 2 It can be seen that the NMR peak of the first polymer confirms that the N-4-vinylphenyl-N,N-dimethylamine monomer is added to the polystyrene main chain.

[0052] Then the second stage of polymerization is initiated again. Figure 3The following are the hydrogen spectra of the final grafted block copolymer, the first stage polymerization product, and the pure acrylate polymer in CDCl3. It can be observed that the second polymer was successfully grafted.

[0053] Figure 4 The GPC spectra of the purified first-stage polymer and the final block product (THF as the mobile phase) are schematically shown. The first-stage polymer has a number-average molecular weight (Mn) of 11,035, a weight-average molecular weight (Mw) of 14,958, and a PDI of 1.35. The block polymer has a number-average molecular weight (Mn) of 45,301, a weight-average molecular weight (Mw) of 236,843, and a PDI of 5.22.

[0054] Example 2

[0055] Styrene monomer (10 ml of the following structure) and N-4-vinylphenyl-N,N-dimethylamine monomer were mixed in a ratio of 20:1. Then, 40 ml of toluene and 0.07 g of AIBN were added. The mixture was reacted at 85°C for 6 hours to obtain a mixture. The mixture was dissolved in dichloromethane and then added dropwise to anhydrous petroleum ether. The solution produced a precipitate, which was then filtered, cleaned, and dried to obtain the purified first-stage polystyrene polymer compound.

[0056]

[0057] The first-stage polymer (0.5 g) was mixed again with monomer E1 (1.5 ml) and imide compound B7 (0.01 g). The mixture was irradiated under a 365 nm, 10 W light source for 1 hour to complete the polymerization reaction. The polymerization product was dissolved in dichloromethane and then back-dripped into anhydrous petroleum ether to produce a precipitate. The solution was then filtered, cleaned, and dried to obtain the purified grafted polymer brush copolymer.

[0058]

[0059] Figure 5 The GPC spectra of the purified first-stage polymer and the final block product (THF as the mobile phase) are schematically shown. The first-stage polymer has a number-average molecular weight (Mn) of 11,937, a weight-average molecular weight (Mw) of 18,227, and a PDI of 1.52. The block polymer has a number-average molecular weight (Mn) of 50,186, a weight-average molecular weight (Mw) of 215,541, and a PDI of 4.29.

[0060] Example 3

[0061] Styrene monomer (10 ml of the following structure) and N-4-vinylphenyl-N,N-dimethylamine monomer (10 ml of styrene monomer) were mixed in a 10:1 ratio. Then, 40 ml of toluene and 0.07 g of AIBN were added. The mixture was reacted at 85°C for 6 hours to obtain a mixture. The mixture was dissolved in dichloromethane and then added dropwise to anhydrous petroleum ether. The solution produced a precipitate, which was then filtered, cleaned, and dried to obtain the purified first-stage polystyrene polymer compound.

[0062]

[0063] The first-stage polymer (0.5 g) was mixed again with monomer E2 (1.5 ml) and imide compound B7 (0.01 g). The mixture was irradiated for 1 hour under a 365 nm, 10 W light source to complete the polymerization reaction. The polymerization product was dissolved in dichloromethane and then back-dripped into anhydrous petroleum ether to produce a precipitate. The solution was then filtered, cleaned, and dried to obtain the purified grafted polymer brush copolymer.

[0064]

[0065] Figure 6 This is the hydrogen spectrum of the first stage polymer prepared in this example in CDCl3.

[0066] Figure 7 The GPC spectra of the purified first-stage polymer and the final block product (THF as the mobile phase) are schematically shown. The first-stage polymer has a number-average molecular weight (Mn) of 9,054, a weight-average molecular weight (Mw) of 13,496, and a PDI of 1.49. The block polymer has a number-average molecular weight (Mn) of 41,313, a weight-average molecular weight (Mw) of 144,283, and a PDI of 3.49.

[0067] 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 preparing a grafted polymer brush copolymer, characterized in that: The following steps are involved: S1. Styrene monomer, N-4-vinylphenyl-N,N-dimethylamine, toluene, and AIBN are mixed, heated, and reacted to form a first-stage polymer; S2. Mixing the first-stage polymer with an acrylate monomer and an imide compound, and continuing the reaction under light conditions to obtain a polymer brush copolymer.

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

4. The preparation method according to claim 1, characterized in that The structure of the acrylic acid ester monomer is: where R 29 represents hydrogen or methyl. R 30 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.

5. The preparation method according to claim 4, characterized in that The acrylic acid ester monomer is selected from one of the following structures:

6. The preparation method according to claim 1, characterized in that The heating temperature in S1 is 40° C.-100° C.; and the reaction time is 2 h-24 h.

7. The preparation method according to claim 1, characterized in that The illumination condition in S2 is ultraviolet light or visible light with a wavelength of 280nm to 600nm, and the illumination time is 1s to 5h.

8. The preparation method according to claim 1, characterized in that The molar ratio of the imide compound to the acrylate monomer is 1:(1-1000).

9. The method according to claim 1, characterized in that The method further includes a polymer purification step: dissolving the first-stage polymer in S1 or the high-molecular-weight brush copolymer 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 stage polymer can reach more than 10,000, and the weight average molecular weight can reach more than 10,000; the number average molecular weight of the polymer brush copolymer can reach more than 20,000, and the weight average molecular weight can reach more than 100,000.

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