Macromolecular RAFT (reversible addition-fragmentation chain transfer) polymer, preparation method and application thereof in RAFT reaction

Abstract

The invention belongs to the field of RAFT (reversible addition-fragmentation chain transfer) polymerization reaction, and particularly discloses a macromolecular RAFT polymer, a preparation method and application of the macromolecular RAFT polymer in RAFT reaction. The macromolecular RAFT polymer at least comprises a block Z-[A] x-b-[B] y; wherein Z is a small molecule RAFT group; the block [A] x is formed by double-bond addition polymerization of hydrophilic monomers, and the hydrophilic monomers are C7-C20 quaternary ammonium salt monomers and / or sulfonate monomers; the block [B] y is formed by double-bond addition polymerization of a hydrophobic monomer, and the hydrophobic monomer is a C10-C22 methacrylate or acrylate monomer. The hydrophilic monomer with the quaternary ammonium salt monomer and / or the sulfonate monomer is selected to construct the hydrophilic chain segment, and meanwhile, the C10-C22 acrylate monomer / methacrylate monomer with strong hydrophobicity is introduced, so that the emulsifying property of the macromolecular RAFT reagent is improved.

Description

Technical Field

[0001] This application belongs to the field of RAFT polymerization reaction, and more specifically, relates to a macromolecular RAFT polymer, its preparation method and its application in RAFT reaction. Background Technology

[0002] Long-chain alkyl acrylate emulsions, due to their excellent hydrophobic properties, have been widely used in various industrial fields such as coatings, textile finishing, and paper processing. In recent years, with the continuous improvement of application requirements for emulsion performance, research has shown two related development directions: one is to achieve precise control of polymer molecular structure through controlled living polymerization technology, thereby optimizing its final performance; the other is to minimize or replace the use of traditional small-molecule emulsifiers to overcome the negative impacts such as surface defects, decreased water resistance, and environmental burden caused by their migration and precipitation. Against this background, reversible addition-fragmentation chain transfer (RAFT) polymerization, as an important living / controlled free radical polymerization method, has been gradually applied to the synthesis research of acrylate emulsions. By using amphiphilic macromolecular RAFT reagents with both chain transfer activity and emulsification function to replace traditional small-molecule emulsifiers, not only can the emulsion polymerization process be effectively controlled, but the performance defects caused by small-molecule emulsifier residues can also be significantly reduced, thus providing a new approach for the application of RAFT emulsion polymerization in the preparation of high-performance acrylate polymers.

[0003] Existing reports indicate that RAFT emulsion polymerization of short-chain alkyl groups (such as acrylates with side chain carbons < 6) in the aqueous phase can be successfully achieved using amphiphilic macromolecular RAFT reagents without the addition of external small-molecule emulsifiers. Currently reported hydrophilic monomers used to construct amphiphilic macromolecular RAFT reagents mainly include acrylic acid (AA), methacrylic acid (MAA), hydroxyethyl acrylate (HEA), and hydroxypropyl acrylate (HPA); while commonly used hydrophobic monomers are mainly styrene (St) and short-chain (meth)acrylates with side chain carbons less than 4.

[0004] However, compared to short-chain alkyl acrylate monomers, long-chain alkyl acrylate monomers (with ≥10 carbon atoms in the side chain) are significantly more difficult to emulsify due to their enhanced hydrophobic properties. Existing amphiphilic macromolecular RAFT reagents have relatively weak emulsifying abilities and are unable to achieve complete emulsification of long-chain alkyl acrylate monomers. Therefore, without the addition of small-molecule emulsifiers, effective RAFT emulsion polymerization of long-chain alkyl acrylate copolymers cannot yet be achieved.

[0005] Synthesizing macromolecular RAFT reagents with strong emulsifying capabilities requires the simultaneous introduction of both strongly hydrophilic and strongly hydrophobic monomers; however, these two monomers have significantly different requirements for solvent polarity. Furthermore, the hydrophilic / hydrophobic properties of the macromolecular chains continuously and dynamically change during polymerization, posing a significant challenge to solvent selection in the reaction system. The difficulty in finding a universal solvent system that simultaneously satisfies the requirements of initial monomer dissolution, intermediate product stability, and final polymer dispersion makes the successful implementation of this polymerization reaction extremely difficult. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the purpose of this application is to synthesize a macromolecular RAFT polymer with strongly hydrophilic and strongly hydrophobic monomers, aiming to solve the problem of polymerization of long side-chain alkyl acrylate monomers.

[0007] To achieve the above objectives, this application provides a macromolecular RAFT polymer, wherein the macromolecular RAFT polymer comprises at least the Z-[A] block. x -b-[B] y ; Where Z is a small molecule RAFT group; Block [A] x It is formed by the addition polymerization of hydrophilic monomers via double bonds, wherein the hydrophilic monomers are C7-C20 quaternary ammonium salt monomers and / or sulfonate monomers; Block [B] y It is formed by the addition polymerization of hydrophobic monomers via double bonds, wherein the hydrophobic monomers are C10-C22 methacrylates or acrylate monomers; -b- indicates [A] x and [B] y It exists in the form of a block, where x and y are each independently between 3 and 50.

[0008] Preferably, the number-average molecular weight of the macromolecular RAFT polymer is 2000-7000.

[0009] Preferably, the small molecule RAFT group includes a carboxylic acid group, a dithioester group, and / or a trithioester group.

[0010] Preferably, the quaternary ammonium salt monomer is one or more of (meth)acryloyloxyethyltrimethylammonium chloride, diallyl dimethylammonium chloride, or (meth)acrylate dimethylaminoethyl ester; the sulfonate monomer is 2-acrylamido-2-methylpropanesulfonic acid and / or sodium styrene sulfonate.

[0011] Preferably, the hydrophobic monomer is a C10, C12, C16 or C18 methacrylate or acrylate monomer.

[0012] Secondly, this application provides a method for preparing the above-mentioned macromolecular RAFT polymer, comprising the following steps: S1: The small molecule RAFT reagent and hydrophilic monomer are dissolved in a low-alcohol solvent, and then the first initiator is added under an inert atmosphere. The first polymerization reaction is carried out at a temperature of 50℃~85℃ to obtain a polymer Z[A] containing the first block polymer. x The first solution; the molar ratio of the small molecule RAFT reagent to the hydrophilic monomer is 1:50 to 1:3; S2: Add a hydrophobic monomer dissolved in an ether solvent to the first solution obtained in step S1, add a second initiator under an inert atmosphere, and add a system stabilizer multiple times at a temperature of 50℃~85℃ to carry out a second polymerization reaction to obtain the macromolecular RAFT polymer; the molar ratio of the small molecule RAFT reagent to the hydrophobic monomer is 1:50~1:3.

[0013] Preferably, the first initiator and the second initiator are azo initiators; the mass of the first initiator is 0.2% to 6% of the mass of the hydrophilic monomer, and the mass of the second initiator is 0.2% to 6% of the mass of the hydrophobic monomer.

[0014] As a further preferred embodiment, the azo initiator is azobisisobutyramidine hydrochloride and / or 4,4'-azobis(4-cyanopentanoic acid).

[0015] Preferably, the small molecule RAFT reagent in step S1 is a carboxylic acid, dithioester, or trithioester small molecule RAFT reagent.

[0016] As a further preferred embodiment, the small molecule RAFT reagent is one or more of the following: 2-(((dodecylthio)carbonthio)thio)propionic acid, 4-cyano-4-(phenylcarbonthio)pentanoic acid, 2-(((ethylthio)carbonthio)thio)propionic acid, cyanoisopropyl dithiobenzoate, 2-phenyl-2-propylphenyl dithioester, bis(thiobenzoyl) disulfide, and 2-(dodecyltrithiocarbonate)-2-methylpropionic acid.

[0017] Preferably, in step S1, the mass ratio of the hydrophilic monomer to the low-alcohol solvent is 1:8 to 1:15.

[0018] Preferably, the low-alcohol solvent in step S1 is a C1-C4 alcohol; more preferably, the low-alcohol solvent is one or more of ethanol, isopropanol, or n-butanol.

[0019] Preferably, the system stabilizer is added three times or more in step S2, and the system stabilizer is one or more of ethanol, propanol, isopropanol, n-butanol, tert-butanol, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol methyl ether, or tripropylene glycol methyl ether.

[0020] Preferably, the mass ratio of the system stabilizer to the ether solvent in step S2 is 1:7 to 1:4.

[0021] Preferably, the ether solvent in step S2 is a C4-C12 cyclic ether; more preferably, the cyclic ether is 1,4-dioxane and / or tetrahydrofuran.

[0022] Preferably, after step S2, the process further includes cooling and drying to obtain a solid macromolecular RAFT polymer.

[0023] As a further preferred embodiment, the drying temperature is below 120°C.

[0024] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. This application uses hydrophilic monomers containing quaternary ammonium salt monomers and / or sulfonate monomers to construct hydrophilic segments, and introduces C10-C22 acrylate monomers / methacrylate monomers with strong hydrophobicity to prepare amphiphilic macromolecular RAFT polymers that have both excellent chain transfer activity and good emulsification ability for long-chain alkyl acrylates, thereby improving the emulsification performance of macromolecular RAFT reagents; 2. Compared with traditional hydrophobic monomers, strongly hydrophobic C10-C22 acrylate monomers or methacrylate monomers not only have stronger hydrophobic properties, but also significantly improve their compatibility with polymerizing monomers when used in subsequent RAFT reactions, further effectively enhancing the emulsification stability of amphiphilic block polymers in emulsion systems. 3. During the preparation process, low-alcohol solvents are used to dissolve hydrophilic monomers, and ether solvents are used to dissolve hydrophobic monomers to ensure that each is fully dissolved, while controlling the polarity difference between the two solvents to prevent it from being too large; 4. By introducing a system stabilizer, the significant differences in polarity and compatibility between strongly hydrophilic and strongly hydrophobic monomers can be effectively overcome, thus maintaining the homogeneity and stability of the reaction system. Based on the multiple additions of the system stabilizer during the polymerization process, by adjusting the solvent polarity and compatibility, it is ensured that the strongly hydrophilic monomer, strongly hydrophobic monomer, intermediate products, and the final macromolecular RAFT reagent can all exist stably in the entire reaction system, thereby successfully achieving a stable and controllable polymerization reaction. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Furthermore, throughout this specification, references to "an embodiment"; "an embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. Therefore, the appearance of the phrase "in one embodiment;" throughout this specification, and similar language, may, but not necessarily, refer to the same embodiment.

[0028] This application provides a macromolecular RAFT polymer and its preparation method. The macromolecular RAFT polymer is formed by two polymerization steps of a small molecule RAFT reagent, a hydrophilic monomer, and a hydrophobic monomer, and has a number average molecular weight of 2000-7000.

[0029] Among them, the small molecule RAFT reagent is a carboxylic acid, dithioester or trithioester small molecule RAFT reagent, such as 2-(((dodecylthio)carbonthio)thio)propionic acid, 4-cyano-4-(phenylcarbonthio)pentanoic acid, 2-(((ethylthio)carbonthio)thio)propionic acid, cyanoisopropyl dithiobenzoate, 2-phenyl-2-propylphenyl dithioester, bis(thiobenzoyl) disulfide, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid or one or more of these.

[0030] Hydrophilic monomers are C7-C20 quaternary ammonium salt monomers (organic compounds containing a quaternary ammonium cationic group and a polymerizable vinyl group in their molecular structure) and / or sulfonate monomers (organic compounds containing a sulfonate anionic group and a polymerizable vinyl group in their molecular structure); for example, (meth)acryloyloxyethyltrimethylammonium chloride, diallyl dimethylammonium chloride or (meth)acrylate dimethylaminoethyl ester, 2-acrylamido-2-methylpropanesulfonic acid and / or sodium styrene sulfonate, etc.

[0031] The hydrophobic monomer is a C10-C22 methacrylate or acrylate monomer; for example, a C10, C12, C16 or C18 methacrylate or acrylate monomer.

[0032] The preparation method of this macromolecular RAFT polymer specifically includes the following steps: S1: Dissolve the small molecule RAFT reagent and hydrophilic monomer in a 1:x ratio in a low-alcohol solvent with a mass of 8-15 times that of the hydrophilic monomer. Then, under an inert atmosphere, add 0.2%-6% of an azo initiator (equivalent to the mass of the hydrophilic monomer) and carry out the first polymerization reaction at the reaction temperature of the azo initiator (generally 50℃-85℃) to obtain the first block polymer Z[A]. x The first solution; Where x is 3 to 50, and the low alcohol solvent is a C1-C4 alcohol, such as one or more of ethanol, isopropanol or n-butanol.

[0033] S2: Add a hydrophobic monomer dissolved in an ether solvent (the amount of hydrophobic monomer is y times the amount of the small molecule RAFT reagent) to the first solution obtained in step S1. Under an inert atmosphere, add 0.2% to 6% of an azo initiator (such as azobisisobutyramidine hydrochloride and / or 4,4'-azobis(4-cyanopentanoic acid)). At the reaction temperature of the azo initiator (generally 50℃ to 85℃), add a system stabilizer three or more times (total mass is 1 / 7 to 1 / 4 of the total mass of the ether solvent), and carry out the second polymerization reaction to obtain the macromolecular RAFT polymer Z-[A]. x -b-[B] y The solution; -b- indicates [A] x and [B] y It exists in the form of a segment; Wherein, y is 3~50, the system stabilizer is one or more of ethanol, propanol, isopropanol, n-butanol, tert-butanol, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol methyl ether or tripropylene glycol methyl ether; the ether solvent is a C4-C12 cyclic ether such as 1,4-dioxane and / or tetrahydrofuran. S3: Cool down and dry at 120°C to obtain a solid macromolecular RAFT polymer.

[0034] Example 1 In this embodiment, the small molecule RAFT reagent is DDMAT, i.e., 2-(dodecyltrithiocarbonate)-2-methylpropionic acid (molecular weight 364.63), the hydrophilic monomer is DMC, i.e., methacryloyloxyethyltrimethylammonium chloride (molecular weight 207.698), the initiator is V501, i.e., 4,4'-azobis(4-cyanopentanoic acid), and the low alcohol solvent is ethanol; the hydrophobic monomer is LA, i.e., dodecyl acrylate (molecular weight 240.38), the ether solvent is 1,4-dioxane, and the solvent system stabilizer is ethanol.

[0035] S1: Add 1.1 g of small molecule RAFT reagent, 5.0 g of hydrophilic monomer, and 55 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 4% (by weight) of the initiator (dissolved in 5 g of low-alcohol solvent) to the reaction system, and react for 6 h before cooling to room temperature.

[0036] S2: Subsequently, 3.9 g of hydrophobic monomer dissolved in 25 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 1% (by weight) of the initiator (dissolved in 5 g of ether solvent) was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 2 g of solvent system stabilizer was added to the system every 3 h for a total of three times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0037] Calculations show x≈8, y≈5.4, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 3300.

[0038] Example 2 In this embodiment, the small molecule RAFT reagent is CPPA, namely 4-cyano-4-(phenylcarbothioylthio)pentanoic acid (molecular weight 98.176), the hydrophilic monomer is DADMAC, namely dimethyl diallyl ammonium chloride (molecular weight 161.67), the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is isopropanol, the hydrophobic monomer is tetradecyl acrylate (molecular weight 268.43), the ether solvent is tetrahydrofuran, and the solvent system stabilizer is ethanol.

[0039] S1: Add 0.4 g of small molecule RAFT reagent, 6.0 g of hydrophilic monomer, and 50 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 2% (by weight) of the initiator (by mass of the hydrophilic monomer) dissolved in 5 g of low-alcohol solvent to the reaction system. After reacting for 6 h, cool to room temperature.

[0040] S2: Subsequently, 3.4 g of hydrophobic monomer dissolved in 30 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 2% (by weight) of the initiator dissolved in 5 g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 9 h. During the reaction, 1.5 g of solvent system stabilizer was added to the system every 2 h, for a total of four times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0041] Calculations show x≈9.1, y≈3, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 2405.

[0042] Example 3 In this embodiment, the small molecule RAFT reagent is CPDB, i.e., cyanoisopropyl dithiobenzoate (molecular weight 221.33), the hydrophilic monomer is dimethyl diallyl ammonium chloride (molecular weight 161.67), the initiator is V501, i.e., 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is ethanol; the hydrophobic monomer is dodecyl methacrylate (molecular weight 254.41), the ether solvent is tetrahydrofuran, and the solvent system stabilizer is isopropanol.

[0043] S1: Add 0.6 g of small molecule RAFT reagent, 5.5 g of hydrophilic monomer, and 55 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 5% (by weight) of the initiator (hydrophilic monomer) dissolved in 5 g of low-alcohol solvent to the reaction system. After reacting for 6 h, cool to room temperature.

[0044] S2: Subsequently, 5.0 g of hydrophobic monomer dissolved in 30 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 1% (by weight) of the initiator dissolved in 5 g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 2 g of solvent system stabilizer was added to the system every 3 h for a total of three times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0045] Calculations show x≈12.5, y≈7.2, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 4074.

[0046] Example 4 In this embodiment, the small molecule RAFT reagent is CDB, namely 2-phenylprop-2-ylphenyl dithiocarbamate (molecular weight 272.41), the hydrophilic monomer is acryloyloxyethyltrimethylammonium chloride (molecular weight 193.67), the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is isopropanol; the hydrophobic monomer is dodecyl acrylate (molecular weight 240.38), the ether solvent is tetrahydrofuran, and the solvent system stabilizer is propylene glycol methyl ether.

[0047] S1: Add 1.0 g of small molecule RAFT reagent, 6.4 g of hydrophilic monomer, and 60 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 3% (by weight) of the initiator (by mass of the hydrophilic monomer) dissolved in 8 g of low-alcohol solvent to the reaction system. After reacting for 8 h, cool to room temperature.

[0048] S2: Subsequently, 7 g of hydrophobic monomer dissolved in 40 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 1% (by weight) of the initiator dissolved in 8 g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 2 g of solvent system stabilizer was added to the system every 2 h, for a total of four times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0049] Calculations show x≈9, y≈8, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 3923.

[0050] Example 5 In this embodiment, the small molecule RAFT reagent is DDMAT, namely 2-(dodecyltrithiocarbonate)-2-methylpropionic acid (molecular weight 364.63), the hydrophilic monomer is 2-acrylamido-2-methylpropanesulfonic acid (molecular weight 207.24), the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is ethanol; the hydrophobic monomer is tetradecyl methacrylate (molecular weight 282.5), the ether solvent is 1,4-dioxane, and the solvent system stabilizer is isopropanol.

[0051] S1: Add 1.2 g of small molecule RAFT reagent, 10.2 g of hydrophilic monomer, and 100 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 2% (by weight) of the initiator (dissolved in 8 g of low-alcohol solvent) to the reaction system, and react for 8 h before cooling to room temperature.

[0052] S2: Subsequently, 8.3 g of hydrophobic monomer dissolved in 50 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 2% (by weight) of the initiator dissolved in 5 g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 2.5 g of solvent system stabilizer was added to the system every 2 h, for a total of four times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0053] Calculations show x≈15, y≈9, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 5986.

[0054] Example 6 In this embodiment, the small molecule RAFT reagent is DTPA, namely 2-(((dodecylthio)carbonthio)thio)propionic acid (molecular weight 350.58), the hydrophilic monomer is methacryloyloxyethyltrimethylammonium chloride (molecular weight 207.698), the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is isopropanol, the hydrophobic monomer is hexadecyl acrylate (molecular weight 296.48), the ether solvent is dioxane, and the solvent system stabilizer is n-butanol.

[0055] S1: Add 1.5 g of small molecule RAFT reagent, 9.4 g of hydrophilic monomer, and 100 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 4% (by weight) of the initiator (dissolved in 8 g of low-alcohol solvent) to the reaction system, and react for 8 h before cooling to room temperature.

[0056] S2: Subsequently, 8.9 g of hydrophobic monomer dissolved in 50 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 3% (by weight) of the initiator dissolved in 8 g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 3 g of solvent system stabilizer was added to the system every 2 h, for a total of four times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0057] Calculations show x≈10.6, y≈7, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 4628.

[0058] Example 7 In this embodiment, the small molecule RAFT reagent is DTPA, namely 2-(((dodecylthio)carbonthio)thio)propionic acid (molecular weight 350.58), the hydrophilic monomer is 2-acrylamido-2-methylpropanesulfonic acid (molecular weight 207.24), the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is ethanol; the hydrophobic monomer is dodecyl acrylate (molecular weight 240.38), the ether solvent is tetrahydrofuran, and the solvent system stabilizer is isopropanol.

[0059] S1: Add 1.1 g of small molecule RAFT reagent, 4.5 g of hydrophilic monomer, and 40 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 2% (by weight) of the initiator (by mass of the hydrophilic monomer) dissolved in 5 g of low-alcohol solvent to the reaction system. After reacting for 8 h, cool to room temperature.

[0060] S2: Subsequently, 3.8g of hydrophobic monomer dissolved in 25g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80℃. A solution of 1% (by weight) of the initiator dissolved in 5g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 1.5g of solvent system stabilizer was added to the system every 3 h, for a total of three times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110℃ to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0061] Calculations show x≈7, y≈5, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 2996.

[0062] Example 8 In this embodiment, the small molecule RAFT reagent is CDB, namely 2-phenylprop-2-ylphenyl dithiocarbamate (molecular weight 272.41), the hydrophilic monomer is 2-acrylamido-2-methylpropanesulfonic acid (molecular weight 207.24), the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid), the low alcohol solvent is n-butanol; the hydrophobic monomer is tetradecyl methacrylate (molecular weight 282.45), the ether solvent is dioxane, and the solvent system stabilizer is dipropylene glycol methyl ether.

[0063] S1: Add 1.0 g of small molecule RAFT reagent, 8.4 g of hydrophilic monomer, and 80 g of low-alcohol solvent to a four-necked flask, and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 2% (by weight) of the initiator (dissolved in 5 g of low-alcohol solvent) to the reaction system, and react for 8 h before cooling to room temperature.

[0064] S2: Subsequently, 5.2 g of hydrophobic monomer dissolved in 30 g of ether solvent was added, stirred thoroughly to dissolve, and then the mixture was purged with nitrogen at room temperature for 30 min to remove oxygen, followed by heating to 80 °C. A solution of 2% (by weight) of the initiator dissolved in 8 g of ether solvent was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 2 g of solvent system stabilizer was added to the system every 3 h, for a total of three times. After the reaction was completed, the yellow liquid in the flask was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target amphiphilic macromolecular RAFT reagent, i.e., the macromolecular RAFT polymer of this application.

[0065] Calculations show x≈11, y≈5, and the molecular weight of the amphiphilic macromolecule RAFT reagent is approximately 3977.

[0066] Comparative Example 1 The same steps as in Example 1 were repeated, except that the low-alcohol solvent in step S1, the ether solvent in step S2, and the solvent system stabilizer were all a mixture of ethanol and dioxane in a mass ratio of 2:1.

[0067] Comparative Example 2 In this embodiment, the small molecule RAFT reagent is 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, the hydrophilic monomer is acrylic acid, the initiator is V501, namely 4,4'-azobis(4-cyanopentanoic acid); the hydrophobic monomer is styrene, and the ether solvent and solvent system stabilizer are dioxane.

[0068] S1: Add 1.1 g of small molecule RAFT reagent, 5.9 g of hydrophilic monomer, and 55 g of low-alcohol solvent to a four-necked flask and stir until completely dissolved. While stirring continuously, purge with nitrogen gas at room temperature for 30 min to remove oxygen, then raise the temperature to 80 °C. Slowly add a solution of 4% (by weight) of the initiator (dissolved in 5 g of dioxane) to the reaction system dropwise. After reacting for 6 h, cool to room temperature.

[0069] S2: Subsequently, 3.0 g of hydrophobic monomer dissolved in 25 g of ether solvent was added, and the mixture was stirred thoroughly to dissolve. The mixture was then deoxygenated again by purging with nitrogen at room temperature for 30 min, and the temperature was raised to 80 °C. A solution of 1% (by weight) of the initiator (dissolved in 5 g of ether solvent) was slowly added dropwise to the reaction system, and the reaction was continued for 10 h. During the reaction, 2 g of solvent system stabilizer was added to the system every 3 h, for a total of three times. After the reaction was completed, the yellow liquid in the bottle was transferred and dried at 110 °C to remove the solvent, yielding a light yellow waxy solid, which is the target copolymer.

[0070] Comparative Example 3 The same steps as in Example 1 were repeated, except that in step S2, after the reaction continued for 10 h, 6 g of solvent system stabilizer was added to the reaction system at once.

[0071] Experimental Results Test 1 Add 5 g of octadecyl acrylate and 50 g of deionized water to a beaker, and add 1 g of the macromolecular RAFT reagent synthesized in the examples and comparative examples, respectively. Treat with ultrasonic power of 250 W for 10 minutes, then let stand at room temperature for 2 hours, and observe and record the state of the emulsion. The results are shown in Table 1.

[0072] Table 1. Emulsification test results of the examples and comparative examples.

[0073] The results above show that the amphiphilic macromolecular RAFT reagent synthesized using the technology of this application exhibits stable reaction process and excellent emulsifying ability, enabling complete emulsification of long-chain alkyl acrylate monomers with ≥10 carbon atoms in the side chain. In contrast, the comparative example, where a mixed solvent was used directly as the reaction medium, showed poor system stability and was prone to precipitation during the reaction, resulting in the failure to successfully synthesize the target macromolecular RAFT reagent.

[0074] Experimental Results Test 2: RAFT Emulsion Polymerization of Side-Long-Chain Alkyl Acrylates Test Example 2-1 Step A: Add 0.9g of the amphiphilic macromolecular RAFT reagent from Example 1, 8.3g of dodecyl acrylate and 45g of deionized water to a four-necked flask, and sonicate to form a homogeneous preemulsion. Step B: With continuous stirring, nitrogen gas was bubbled through the system at room temperature for 30 min to remove oxygen, and then the temperature was raised to 80 °C. A solution of 0.1 g potassium persulfate dissolved in 5 g deionized water was slowly added dropwise to the system, and the reaction was allowed to proceed for 5 h before cooling to room temperature. Then, 0.8 g glycidyl methacrylate was added, and the mixture was stirred thoroughly to ensure homogeneous emulsification. Step C: Nitrogen was purged again at room temperature for 30 min to remove oxygen, and then the temperature was raised to 80 °C. A solution of 0.01 g potassium persulfate dissolved in 1.5 g deionized water was slowly added dropwise to the reaction system, and the reaction was continued for 3 h. After cooling to room temperature, a long-chain alkyl acrylate block copolymer emulsion was finally obtained. The appearance of the emulsion was observed, and the average particle size of the polymer was tested by dynamic light scattering. The results are shown in Table 2.

[0075] Test Example 2-2 Step A: Add 1.2 g of the amphiphilic macromolecular RAFT reagent from Example 2, 7.2 g of octadecyl acrylate and 45 g of deionized water to a four-necked flask, and sonicate to form a homogeneous preemulsion. Step B: With continuous stirring, nitrogen gas was bubbled through the system at room temperature for 30 min to remove oxygen, and then the temperature was raised to 80 °C. A solution of 0.1 g potassium persulfate dissolved in 5 g deionized water was slowly added dropwise to the system, and the reaction was allowed to proceed for 5 h before cooling to room temperature. Then, 1.6 g of isobornyl methacrylate was added, and the mixture was stirred thoroughly to ensure homogeneous emulsification. Step C: Nitrogen was purged again at room temperature for 30 min to remove oxygen, and then the temperature was raised to 80 °C. A solution of 0.01 g potassium persulfate dissolved in 1.5 g deionized water was slowly added dropwise to the reaction system, and the reaction was continued for 3 h. After cooling to room temperature, a long-chain alkyl acrylate block copolymer emulsion was finally obtained. The appearance of the emulsion was observed, and the average particle size of the polymer was tested by dynamic light scattering method. The results are shown in Table 2.

[0076] Test Example 2-3 Step A: Add 1.0g of the amphiphilic macromolecular RAFT reagent from Example 3, 7.8g of octadecyl methacrylate and 45g of deionized water to a four-necked flask, and sonicate to form a homogeneous preemulsion. Step B: With continuous stirring, nitrogen gas was bubbled through the system at room temperature for 30 minutes to remove oxygen, and then the temperature was raised to 80 °C. A solution of 0.1 g potassium persulfate dissolved in 5 g deionized water was slowly added dropwise to the system, and the reaction was allowed to proceed for 5 hours before cooling to room temperature. Then, 0.75 g hydroxyethyl acrylate was added, and the mixture was stirred thoroughly to ensure homogeneous emulsification. Step C: Nitrogen was purged again at room temperature for 30 min to remove oxygen, and then the temperature was raised to 80 °C. A solution of 0.01 g potassium persulfate dissolved in 1.5 g deionized water was slowly added dropwise to the reaction system, and the reaction was continued for 3 h. After cooling to room temperature, a long-chain alkyl acrylate block copolymer emulsion was finally obtained. The appearance of the emulsion was observed, and the average particle size of the polymer was tested by dynamic light scattering method. The results are shown in Table 2.

[0077] Table 2 Results of RAFT reaction in the examples

[0078] The same test was performed using the conventional amphiphilic macromolecular RAFT reagent of Comparative Example 2-1. However, the polymerization reaction could not be completed because it could not emulsify.

[0079] Based on Example 1, the mass of the hydrophilic monomer (and the mass of the initiator and low-alcohol solvent were increased or decreased proportionally) or the mass of the hydrophobic monomer was adjusted so that the molar ratio of the hydrophilic monomer to the small molecule RAFT reagent and the molar ratio of the hydrophobic monomer to the small molecule RAFT reagent were adjusted between 3:1 and 50:1. It was found that when the number average molecular weight of the final amphiphilic macromolecular RAFT reagent was 2000 to 7000, it exhibited properties similar to those in Example 1.

[0080] Based on Example 1, by increasing or decreasing the mass of the low-alcohol solvent to adjust the mass ratio of low-alcohol to hydrophilic monomer between 8:1 and 12:1, it was found that the final amphiphilic macromolecular RAFT reagent exhibited properties similar to those in Example 1.

[0081] Based on Example 1, by increasing or decreasing the mass of the ether solvent to adjust the mass ratio of the ether solvent to the system stabilizer between 4:1 and 7:1, it was found that the final amphiphilic macromolecular RAFT reagent exhibited properties similar to those in Example 1.

[0082] The amphiphilic macromolecular RAFT reagent developed in this application combines high chain transfer activity with excellent emulsifying ability. Based on this reagent, efficient RAFT emulsion polymerization of side-long-chain alkyl acrylates can be achieved, resulting in block copolymer emulsions with fine and uniform particle size distribution, and good storage and reaction stability.

[0083] Those skilled in the art will readily understand that the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A macromolecular RAFT polymer, characterized in that, comprises at least a block Z-[A] x -b-[B] y ; wherein Z is a small molecule RAFT group; Block [A] x formed by addition polymerization of a hydrophilic monomer which is a C7-C20 quaternary ammonium salt monomer and / or a sulfonate monomer through a double bond; Block [B] y formed by the addition polymerization of a hydrophobic monomer, which is a C10-C22 methacrylate or acrylate monomer, via a double bond; - b- represents [A] x and [B] y x and y are each independently 3 to 50.

2. The macromolecular RAFT polymer of claim 1, wherein, The number average molecular weight is 2000-7000.

3. The macromolecular RAFT polymer of claim 1, wherein The small molecule RAFT group includes a carboxylic acid group, a dithioester group and / or a trithioester group.

4. The macromolecular RAFT polymer of claim 1, wherein The quaternary ammonium salt monomer is one or more of (meth) acryloyloxyethyl trimethyl ammonium chloride, diallyl dimethyl ammonium chloride or dimethylaminoethyl (meth) acrylate; the sulfonate monomer is 2-acrylamido-2-methylpropane sulfonic acid and / or sodium styrene sulfonate.

5. A process for the preparation of the macromolecular RAFT polymer according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: S1: dissolving a small molecule RAFT agent and a hydrophilic monomer in a low alcohol solvent, then adding a first initiator under an inert atmosphere, and carrying out a first polymerization reaction at a temperature of 50-85°C to obtain a first solution containing a first block polymer Z[A] x ; the small molecule RAFT agent and the hydrophilic monomer have a molar ratio of 1:50-1:3; S2: adding a hydrophobic monomer dissolved in an ether solvent to the first solution obtained in step S1, adding a second initiator under an inert atmosphere, and adding a system stabilizer multiple times at a temperature of 50-85 DEG C to carry out a second polymerization reaction to obtain the macromolecular RAFT polymer; the molar ratio of the small molecule RAFT agent to the hydrophobic monomer is 1:50-1:

3.

6. The production method according to claim 5, wherein The small molecule RAFT agent in step S1 is a carboxylic acid, a dithioester or a trithioester small molecule RAFT agent.

7. The production method according to claim 5, wherein The low alcohol solvent in step S1 is a C1-C4 alcohol, and the ether solvent in step S2 is a C4-C12 cyclic ether.

8. The production method according to claim 5, wherein The mass ratio of the system stabilizer to the ether solvent in step S2 is 1:7-1:

4.

9. The production method according to claim 5, wherein The number of times of adding the system stabilizer in step S2 is three or more, and the system stabilizer is one or more of ethanol, propanol, isopropanol, n-butanol, t-butanol, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol methyl ether or tripropylene glycol methyl ether.

10. Use of the macromolecular RAFT polymer of any one of claims 1-4 in a RAFT reaction.

Images