Zwitterionic particle as well as preparation method and application thereof

Abstract

The invention relates to a zwitterionic particle and a preparation method and application thereof, the zwitterionic particle is of a core-shell structure, the shell is a water-soluble zwitterionic polymer, and the core is a water-insoluble cross-linked polymer; the preparation method comprises the following steps: firstly, preparing core-shell polymer particles of which shells are polydiolefin and cores are crosslinked polystyrene or crosslinked polymethacrylate polymers by combining an active anionic polymerization mediated polymerization induced self-assembly technology with a post-polymerization modification technology; then, polydiolefin of a shell layer is hydrolyzed with trifluoroacetic acid, hydroxylated polydiolefin is prepared, hydroxyl is converted into potassium alkoxide, bromoisobutyl ester or a chain transfer reagent, and allyl monomers containing tertiary amine are initiated to be subjected to controllable / active polymerization; and finally, converting the tertiary amine group into a zwitterionic group by using a modification reagent to prepare the core-shell particle of which the shell is a water-soluble zwitterionic polymer and the core is a water-insoluble polymer. According to the invention, the problem of limitation in the aspects of controllability, function expansion and the like in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to zwitterionic particles, a preparation method and application thereof. Background Art

[0002] Due to the charge balance characteristics of the zwitterionic polymer shell, zwitterionic particles form a dense hydration layer through solvation, showing excellent anti-fouling and dispersion stability, and have broad application prospects in the fields of drug delivery, bioimaging and diagnosis, functional coatings and composite materials, catalytic applications, etc. For example, in the field of drug delivery, Fan et al. developed a zwitterionic block copolymer nanomicelle based on poly [2- (N-oxide-N, N-diethylamino) ethyl methacrylate] -b-poly (ε-caprolactone) (OPDEA-b-PCL). Through the unique "anti-mucus adsorption-weak phospholipid binding" synergistic effect, it achieved the first time that oral nanomedicines could efficiently penetrate the mucus-villous barrier and achieve tumor-targeted delivery, and its therapeutic effect was significantly better than that of intravenous preparations (Advanced Materials, 2022, 34 (16): 2109189.). In the field of bioimaging and diagnosis, Liu et al. prepared fluorescent zwitterionic polymer particles with core-shell structure by copolymerizing monomers with aggregation-induced emission properties with zwitterionic monomers 2-methacryloyloxyethyl phosphorylcholine through reversible addition-fragmentation chain transfer polymerization. The particle size was tens of nanometers, and they showed good dispersibility and strong fluorescence properties in aqueous solution, and had excellent biocompatibility and cell uptake performance for A549 cells (RSC Advances, 2014, 4(66): 35137-35143.). In the field of functional coatings and composite materials, Huang et al. prepared fluorescent zwitterionic polymer particles with core-shell structure by copolymerizing monomers with aggregation-induced emission properties with zwitterionic monomers 2-methacryloyloxyethyl phosphorylcholine. The particles were tens of nanometers in size, and showed good dispersibility and strong fluorescence properties in aqueous solution, and had excellent biocompatibility and cell uptake performance for A549 cells (RSC Advances, 2014, 4(66): 35137-35143.). Blending a base polymer with a matrix material reduced bovine serum albumin adsorption by an ultrafiltration membrane by 48%, while also improving membrane flux and anti-fouling performance (Journal of Membrane Science, 2022, 646:120251). In catalytic applications, mesoporous silica particles surface-modified with zwitterionic polymers simultaneously immobilized organophosphorus hydrolases and achieved localized enrichment of substrates such as parathion-methyl (Biochemical Engineering Journal, 2022, 184:108491).

[0003] At present, there are two main methods for preparing zwitterionic particles. The first is traditional solution self-assembly. For example, Wang et al. synthesized polyethylene glycol-b-poly[3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate] zwitterionic block copolymers (PEG-b-PDMAPS) with cleavable biotin attachment points. The zwitterionic block copolymer chains self-assemble in aqueous solution at temperatures below the upper critical solution temperature (UCST), and their UCST is significantly regulated by sodium chloride concentration. Furthermore, bioconjugates of zwitterionic block copolymers and streptavidin were prepared by biotin-streptavidin coupling. This method is expected to be used to synthesize more bioconjugates with different topological structures (Macromolecules, 2017, 50(6), 2284-2295.). However, the traditional solution self-assembly method has disadvantages such as low solid content (<1wt%) and cumbersome operation, which limits the large-scale application and morphology control of zwitterionic particles. The second is the polymerization-induced self-assembly (PISA) technology. For example, Armes et al. conducted dispersion polymerization of the water-soluble monomer [2-(methacryloyloxy)ethyl]dimethyl(3-sulfonic acid propyl)ammonium hydroxide (SBMA) and the hydrophobic monomer 2-hydroxypropyl methacrylate (HPMA) in a sodium chloride aqueous solution through reversible addition-fragmentation chain transfer polymerization, realized the PISA process, and successfully prepared spherical, worm-like and vesicle-like particles with temperature responsiveness, and showed that the zwitterionic particles have strong salt tolerance (Polymer Chemistry, 2015, 6(41), 7264-7273.); Noy et al. used PISA technology to successfully prepare core-shell zwitterionic particles with a particle size of 30-40 nm using a copolymer of arsenic-containing anticancer drug 4-(N-(S-penicillamine acetyl)aminophenylarsonic acid (PENAO) and zwitterionic monomer 2-methacryloyloxyethylphosphorylcholine (MPC) as a stabilizing chain segment and polymethyl methacrylate as a core-forming block. The anti-protein adsorption performance and cytotoxicity of the particles can be significantly affected by regulating the length of the MPC chain segment (ACS Macro Letters, 2019, 8(1): 57-63.). Although particles of various morphologies and compositions have been successfully prepared by combining controllable / "living" polymerization technology with PISA technology, the controllable preparation of zwitterionic particles still faces major challenges. The reason is that the controllability of the zwitterionic polymer synthesis process is insufficient and the preparation of high-purity zwitterionic monomers is difficult, which seriously limits the functional development and application expansion of zwitterionic particles. Summary of the Invention

[0004] The purpose of the present invention is to provide a zwitterionic particle and a preparation method and application thereof in order to solve at least one of the above problems, so as to realize the controllable synthesis of zwitterionic particles.

[0005] The object of the present invention can be achieved by the following technical solution: a zwitterionic particle, wherein the zwitterionic particle has a core-shell structure, the shell is a water-soluble zwitterionic polymer, and the core is a water-insoluble cross-linked polymer.

[0006] Preferably, the zwitterionic polymer is a polydiene-g-betaine polymer.

[0007] Further preferably, the zwitterionic polymer is polyisoprene-g-polymethacrylic acid carboxybetaine, polyisoprene-g-polyacrylic acid carboxybetaine, polyisoprene-g-polymethacrylamide carboxybetaine, polyisoprene-g-polyacrylic acid carboxybetaine, polyisoprene-g-poly 4-vinylpyridine carboxybetaine, polyisoprene-g-poly 2-vinylpyridine carboxybetaine, polyisoprene-g-poly N-vinylimidazole carboxybetaine, polyisoprene-g-poly 2-vinyl-1,3-oxazoline carboxybetaine, polyisoprene-g-poly methacrylic acid sulfobetaine ... 2-vinyl-1,3-oxazoline carboxybetaine, polyisoprene-g-poly 2-vinylpyridine carboxybetaine, polyisoprene-g-poly 2-vinylpyridine carboxybetaine, polyisoprene-g-poly 2-vinylpyridine carboxybetaine, polyisoprene-g-poly 2-vinylpyridine carboxybetaine, polyisoprene-g-poly 2-vinylpyridine carboxybetaine Diene-g-polyacrylic acid sulfobetaine, polyisoprene-g-polymethacrylamide sulfobetaine, polyisoprene-g-polyacrylic acid sulfobetaine, polyisoprene-g-poly 4-vinylpyridine sulfobetaine, polyisoprene-g-poly 2-vinylpyridine sulfobetaine, polyisoprene-g-poly N-vinylimidazole sulfobetaine, polyisoprene-g-poly 2-vinyl-1,3-oxazoline sulfobetaine, polyisoprene-g-polymethacrylic acid phosphobetaine, polyisoprene-g-polyacrylic acid phosphobetaine, polyisoprene-g-polymethacrylamide phosphobetaine, polyisoprene Ethylene-g-polyacrylic acid phosphobetaine, polyisoprene-g-poly 4-vinylpyridine phosphobetaine, polyisoprene-g-poly 2-vinylpyridine phosphobetaine, polyisoprene-g-poly N-vinylimidazole phosphobetaine, polyisoprene-g-poly 2-vinyl-1,3-oxazoline phosphobetaine, polybutadiene-g-poly methacrylic acid carboxybetaine, polybutadiene-g-poly acrylic acid carboxybetaine, polybutadiene-g-polymethacrylamide carboxybetaine, polybutadiene-g-poly acrylic acid carboxybetaine, polybutadiene-g-poly 4-vinylpyridine carboxybetaine, polybutadiene-g-poly 2 -Vinylpyridine carboxybetaine, polybutadiene-g-poly N-vinylimidazole carboxybetaine, polybutadiene-g-poly 2-vinyl-1,3-oxazoline carboxybetaine, polybutadiene-g-poly methacrylic acid sulfobetaine, polybutadiene-g-poly acrylic acid sulfobetaine, polybutadiene-g-polymethacrylamide sulfobetaine, polybutadiene-g-poly acrylic acid sulfobetaine, polybutadiene-g-poly 4-vinylpyridine sulfobetaine, polybutadiene-g-poly 2-vinylpyridine sulfobetaine, polybutadiene-g-poly N-vinylimidazole sulfobetaine, polybutadiene-g-poly 2-vinyl-1,3-oxazoline sulfobetaine, polybutadiene-g-polymethacrylic acid phosphobetaine, polybutadiene-g-polyacrylic acid phosphobetaine, polybutadiene-g-polymethacrylamide phosphobetaine, polybutadiene-g-polyacrylic acid phosphobetaine, polybutadiene-g-poly4-vinylpyridine phosphobetaine, polybutadiene-g-poly2-vinylpyridine phosphobetaine, polybutadiene-g-polyN-vinylimidazole phosphobetaine or polybutadiene-g-poly2-vinyl-1,3-oxazoline phosphobetaine.

[0008] Preferably, the zwitterionic particles have a spherical or worm-like morphology, and the particle size ranges from 25 nm to 2000 nm.

[0009] More preferably, the particle size range of the particles is 25 nm to 1000 nm.

[0010] A method for preparing the zwitterionic particles comprises the following steps:

[0011] S1: Preparation of core-shell polymer particles with a polydiene shell and a cross-linked polystyrene polymer or a cross-linked polymethacrylate polymer as the core using living anionic polymerization-mediated polymerization-induced self-assembly technology;

[0012] S2: hydrolyzing the polydiene in the upper shell of the core-shell polymer particles with trifluoroacetic acid to prepare a hydroxylated polydiene;

[0013] S3: using diphenylmethyl potassium to convert the hydroxyl groups on the hydroxylated polydiene block into potassium alcoholate, thereby initiating living anionic polymerization of tertiary amine-containing olefin monomers; or using bromoisobutyryl bromide to convert the hydroxyl groups on the hydroxylated polydiene block into bromoisobutyl ester, thereby initiating atom transfer radical polymerization of tertiary amine-containing olefin monomers; or using 4-cyano-4-(phenylthioformylthio) pentanoic acid to convert the hydroxyl groups on the hydroxylated polydiene block into a chain transfer agent, thereby initiating reversible addition-fragmentation chain transfer polymerization of tertiary amine-containing olefin monomers; thereby providing the shell polymer with tertiary amine groups;

[0014] S4: using a modification reagent to convert the tertiary amine groups on the shell polymer into zwitterionic groups, thereby preparing zwitterionic particles having a shell of a water-soluble zwitterionic polymer and a core of a water-insoluble cross-linked polymer.

[0015] Preferably, the polymerization-induced self-assembly process in step S1 comprises the following steps:

[0016] (1) dissolving a diene monomer in a solvent, adding butyl lithium, and polymerizing to obtain a polydiene macroinitiator;

[0017] (2) After adding a certain amount of butyl lithium, or directly adding styrene monomers or methacrylate monomers and a crosslinking agent, polymerization is performed to obtain core-shell polymer particles having a shell of polydiene and a core of a crosslinked polystyrene polymer or a crosslinked polymethacrylate polymer.

[0018] Preferably, the cross-linked polystyrene polymer in step S1 is any one or more combinations of polystyrene, poly-α-methylstyrene, poly-p-methylstyrene, poly-m-methylstyrene, poly-p-tert-butylstyrene, poly-p-tert-butoxystyrene, poly-1,1-diphenylethylene, poly-p-methoxystyrene, poly-p-trimethylsiloxystyrene, and poly-4-vinylbiphenyl.

[0019] Further preferably, the cross-linked polystyrene polymer in step S1 is any one or more combinations of polystyrene, poly-p-methylstyrene, poly-p-tert-butoxystyrene, and poly-1,1-diphenylethylene.

[0020] Preferably, the cross-linked polymethacrylate polymer in step S1 is any one or more combinations of polymethyl methacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, poly-tert-butyl methacrylate, poly-n-hexyl methacrylate, poly-n-octyl methacrylate, poly-isooctyl methacrylate, poly-dodecyl methacrylate, poly-octadecyl methacrylate, and poly-ferrocenylmethyl methacrylate.

[0021] Further preferably, the cross-linked polymethacrylate polymer in step S1 is any one or more combinations of polymethyl methacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, and poly-tert-butyl methacrylate.

[0022] Preferably, the polydiene in step S1 is any one of polyisoprene and polybutadiene or a combination thereof.

[0023] Preferably, the solid content of the reaction system during the polymerization-induced self-assembly process in step S1 is 1 to 50 wt%.

[0024] Further preferably, the solid content of the reaction system during the polymerization-induced self-assembly process in step S1 is 5 to 30 wt %.

[0025] Preferably, the solvent in the polymerization-induced self-assembly process in step S1 is any one or more combinations of cyclohexane, n-hexane, n-heptane, n-octane, toluene, and tetrahydrofuran.

[0026] Further preferably, the solvent in the polymerization-induced self-assembly process in step S1 is any one or more combinations of cyclohexane, n-hexane, n-heptane, and tetrahydrofuran.

[0027] Preferably, in the polymerization-induced self-assembly process of step S1, the polymerization temperature is -80 to 100° C., and the polymerization time is 0.5 to 48 h.

[0028] Further preferably, in the polymerization-induced self-assembly process in step S1, the polymerization temperature is -80 to 50° C., and the polymerization time is 0.5 to 12 h.

[0029] Preferably, the crosslinking agent in the polymerization-induced self-assembly process of step S1 is any one or more combinations of divinylbenzene, ethylene glycol dimethacrylate, pentaerythritol tetramethacrylate, and glycerol trimethacrylate.

[0030] Further preferably, the crosslinking agent in the polymerization-induced self-assembly process of step S1 is any one or more combinations of divinylbenzene and ethylene glycol dimethacrylate.

[0031] Preferably, the number average molecular weight of the polydiene in step S1 is 1,000 to 100,000 g / mol, and the number average molecular weight of the cross-linked polystyrene polymer or the cross-linked polymethacrylate polymer is 1,000 to 100,000 g / mol.

[0032] Further preferably, the number average molecular weight of the polydiene in step S1 is 1,000 to 50,000 g / mol, and the number average molecular weight of the cross-linked polystyrene polymer or the cross-linked polymethacrylate polymer is 5,000 to 100,000 g / mol.

[0033] Preferably, the solid content of the reaction system during the hydrolysis process in step S2 is 1 to 30 wt%.

[0034] Further preferably, the solid content of the reaction system during the hydrolysis process in step S2 is 5 to 30 wt%.

[0035] Preferably, the solvent in the hydrolysis process of step S2 is any one or more combinations of tetrahydrofuran, dichloromethane, toluene, methanol, and dioxane.

[0036] Further preferably, the solvent in the hydrolysis process of step S2 is any one or more combinations of tetrahydrofuran, methanol, and dioxane.

[0037] Preferably, in the hydrolysis process of step S2, the reaction temperature is 25-100° C., the reaction time is 0.5-48 h, and the molar ratio of trifluoroacetic acid to the monomer units on the polydiene is 0.1:1-6:1.

[0038] Further preferably, in the hydrolysis process of step S2, the reaction temperature is 25-80° C., the reaction time is 0.5-12 h, and the molar ratio of trifluoroacetic acid to the monomer units on the polydiene is 1:1-2:1.

[0039] Preferably, the tertiary amine-containing vinyl monomer in step S3 is any one or more combinations of 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, 2-(diisopropylamino)ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diisopropylamino)ethyl acrylate, N-(3-dimethylaminopropyl)methacrylamide, N-(2-morpholinoethyl)acrylamide, 2-morpholinoethyl methacrylate, 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, and 2-vinyl-1,3-oxazoline.

[0040] Further preferably, the tertiary amine-containing vinyl monomer in step S3 is any one or more combinations of 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, 2-(diisopropylamino)ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diisopropylamino)ethyl acrylate, 2-morpholinoethyl methacrylate, and 4-vinylpyridine.

[0041] Preferably, the solid content of the polymerization reaction system in step S3 is 1 to 50 wt%.

[0042] More preferably, the solid content of the polymerization reaction system in step S3 is 5 to 30 wt%.

[0043] Preferably, the shell polymer having tertiary amine groups in step S3 is a polytertiary amine polymer with a number average molecular weight of 1,000 to 100,000 g / mol.

[0044] More preferably, the number average molecular weight of the polytertiary amine polymer is 1,000 to 20,000 g / mol.

[0045] Preferably, in step S3, during the living anionic polymerization, the solvent is one of tetrahydrofuran, toluene, and dioxane, or a combination thereof, the temperature is -80 to 25° C., and the reaction time is 0.5 to 6 h.

[0046] More preferably, during the living anionic polymerization, the solvent is tetrahydrofuran, the temperature is -80 to 25° C., and the reaction time is 0.5 to 3 h.

[0047] Preferably, in step S3, during the atom transfer radical polymerization, the solvent is one of toluene, anisole, xylene, ethanol, dimethyl sulfoxide, N,N-dimethylformamide, or a combination thereof, the temperature is 25-100° C., the reaction time is 0.5-48 h, and the catalyst is one of cuprous bromide and tris(2-dimethylaminoethyl)amine, N,N,N′,N′,N″-pentamethyldiethylenetriamine, and tris(2-pyridylmethyl)amine complex, or a combination thereof.

[0048] Further preferably, during atom transfer radical polymerization, the solvent is one of toluene, anisole, and ethanol, or a combination thereof, the temperature is 40 to 80° C., the reaction time is 0.5 to 12 h, and the catalyst is one of cuprous bromide and tris(2-dimethylaminoethyl)amine, N,N,N′,N′,N″-pentamethyldiethylenetriamine, and tris(2-pyridylmethyl)amine complex, or a combination thereof.

[0049] Preferably, in step S3, during the reversible addition-fragmentation chain transfer polymerization, the solvent is one of toluene, anisole, xylene, ethanol, dimethyl sulfoxide, N,N-dimethylformamide or a combination thereof, the temperature is 40-100° C., the reaction time is 0.5-48 h, and the initiator is one of azobisisobutyronitrile, 2,2-azabis(2-imidazoline) dihydrochloride, and 2,2'-azobisisobutylamidine dihydrochloride.

[0050] Further preferably, during the reversible addition-fragmentation chain transfer polymerization, the solvent is one of toluene, anisole, and ethanol, or a combination thereof, the temperature is 40 to 80° C., the reaction time is 0.5 to 12 h, and the initiator is azobisisobutyronitrile.

[0051] Preferably, the modification reagent in step S4 is any one or more combinations of bromoacetic acid, bromopropionic acid, sodium bromoacetate, chloroacetic acid, sodium chloroacetate, sodium 2-bromoethanesulfonate, 2-bromoethyl diethyl phosphate, and 1,3-propane sultone.

[0052] Further preferably, the modification reagent in step S4 is any one or more combinations of bromoacetic acid, bromopropionic acid, sodium 2-bromoethanesulfonate, and 2-bromoethyl diethyl phosphate.

[0053] Preferably, in step S4, the molar ratio of the modification reagent to the tertiary amine group-containing monomer unit on the shell polymer is 0.1:1-2:1, the temperature is 25-100° C., the reaction time is 0.5-48 h, and the solid content of the reaction system is 1-30 wt %.

[0054] Further preferably, the molar ratio of the modification reagent in step S4 to the tertiary amine group-containing monomer unit on the shell polymer is 0.1:1 to 1:1, the temperature is 25 to 70° C., the reaction time is 0.5 to 12 h, and the solid content of the reaction system is 5 to 10 wt %.

[0055] An application of the zwitterionic particles is to use the zwitterionic particles for loading nano-metal catalysts and extracting metal particles from dilute solutions.

[0056] The zwitterionic particles of the present invention can be used as a support for nano-metal catalysts and are also expected to be applied to fields such as extraction of metal particles in dilute solutions.

[0057] The heavy metal loading mechanism of the zwitterionic particles of the present invention is as follows: the zwitterionic polymer in the shell captures heavy metal ions (such as Ag) through electrostatic adsorption and coordination. + or Cu2+ combined with carboxylate), and an external reducing agent is added to reduce the adsorbed metal ions (such as hydrazine hydrate) in situ.

[0058] The working principle of the present invention is:

[0059] In the present invention, first, core-shell polymer particles with different particle sizes and morphologies are prepared using a polymerization-induced self-assembly technique mediated by living anionic polymerization, each comprising a polydiene shell and a cross-linked polystyrene or cross-linked polymethacrylate core. The polydiene in the upper shell of the core-shell polymer particles is then hydrolyzed with trifluoroacetic acid to prepare a hydroxylated polydiene. Subsequently, the hydroxyl groups on the hydroxylated polydiene are converted to potassium alkoxide using diphenylmethyl potassium, initiating living anionic polymerization of tertiary amine-containing olefinic monomers. Alternatively, the hydroxyl groups on the hydroxylated polydiene blocks are converted to bromoisobutyl esters using bromoisobutyl bromide, initiating atom transfer radical polymerization of tertiary amine-containing olefinic monomers. Alternatively, the hydroxyl groups on the hydroxylated polydiene blocks are converted to chain transfer agents using 4-cyano-4-(phenylthioformylthio)pentanoic acid, initiating reversible addition-fragmentation chain transfer polymerization of tertiary amine-containing olefinic monomers. Finally, the tertiary amine groups are converted to zwitterionic groups using a modifying agent, thereby preparing core-shell particles with a water-soluble zwitterionic polymer shell and a water-insoluble cross-linked polymer core. This technology can produce zwitterionic particles with adjustable size, controllable morphology, and stable water dispersion. This method has the advantages of strong universality and high solid content.

[0060] In the present invention, the core and shell are stably bonded by chemical bonding and physical entanglement. Specifically, in step S1, living anionic polymerization directly forms a covalent connection between the core (cross-linked polystyrene or polymethacrylate) and the shell (polydiene); in step S3, the shell-grafted polytertiary amine polymer chain is covalently linked to the shell polymer.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] 1. The composition and molecular weight of the core polymer, shell polymer, and shell graft polymer of the zwitterionic particles prepared by the present invention have good controllability.

[0063] 2. The zwitterionic particles proposed in the present invention have the advantages of adjustable particle size, controllable morphology, simple operation and strong universality.

[0064] 3. The zwitterionic particles proposed in the present invention have excellent water dispersion stability.

[0065] 4. The zwitterionic particles proposed in the present invention can be used as carriers for nanometal catalysts and are also expected to be applied in the environmental field of extracting metal particles from dilute solutions.

[0066] 5. This invention proposes a universal controllable synthesis method for zwitterionic particles to achieve precise structural control and multifunctional integration, and develops applied research. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a transmission electron microscopy (TEM) image of the cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles prepared in Example 1. The average size of the spherical particles is 145 nm.

[0068] Figure 2 This is a transmission electron microscopy (TEM) image of the cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles prepared in Example 5. The worm-like particles have an average length of 450 nm and an average width of 30 nm.

[0069] Figure 3 This is a thermogravimetric curve of the cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles prepared in Example 12 before and after loading with silver. DETAILED DESCRIPTION

[0070] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0071] The present invention provides a zwitterionic particle and a preparation method and application thereof. The zwitterionic particle has a core-shell structure, wherein the shell is a water-soluble zwitterionic polymer and the core is a water-insoluble cross-linked polymer.

[0072] The preparation method is as follows: first, core-shell polymer particles with a shell of polydiene and a core of cross-linked polystyrene or cross-linked polymethacrylate polymer are prepared by using a polymerization-induced self-assembly technology mediated by living anionic polymerization combined with a post-polymerization modification technology; then, the polydiene in the shell is hydrolyzed with trifluoroacetic acid to prepare a hydroxylated polydiene, and the hydroxyl group is converted into potassium alcohol, bromoisobutyl ester or a chain transfer reagent to initiate a controlled / "living" polymerization of a tertiary amine-containing olefin monomer; finally, the tertiary amine group is converted into a zwitterionic group using a modification reagent to prepare core-shell particles with a shell of a water-soluble zwitterionic polymer and a core of a water-insoluble polymer.

[0073] The present invention solves the limitations of the prior art in terms of controllability, function expansion, etc.

[0074] The following describes it in detail with reference to specific embodiments.

[0075] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0076] In the following example, cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles represent zwitterionic particles with a cross-linked polystyrene core and polymethacrylate carboxybetaine grafted onto the surface via polyisoprene.

[0077] Example 1

[0078] This embodiment provides a method for preparing cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles, and the specific steps are as follows:

[0079] (1) Preparation of cross-linked polystyrene@polyisoprene particles

[0080] The designed solid content is 20wt%. First, a 250mL ampoule bottle equipped with a magnetic stirrer is vacuum-baked, and refined n-heptane (120.0mL, 82.08g), tetrahydrofuran (0.05mL, 0.61mmol) and isoprene (9.00mL, 0.0895mol) are added successively with a syringe, and charged with nitrogen. Subsequently, n-butyl lithium (0.60mL, 0.96mmol, 1.60mmol / mL) of metering is added rapidly in the ampoule bottle, and the reaction is carried out for 24h to obtain the polyisoprene macroinitiator, and 0.50mL of the reaction solution is terminated with methanol. The polyisoprene molecular weight M is measured with gel permeation chromatography (GPC). n =12,800 g / mol, M w / M n =1.05; using nuclear magnetic resonance spectroscopy (1 H NMR) showed a conversion of >99%.

[0081] Then, the purified styrene monomer (11.3 mL, 0.0989 mol) was injected into the ampoule via a syringe and the polymerization was continued for 24 h to obtain polyisoprene-b-polystyrene block copolymer. 0.50 mL of the reaction solution was terminated with methanol. The molecular weight M was measured by gel permeation chromatography (GPC). n =37,900 g / mol, M w / M n =1.09; NMR spectrum ( 1 H NMR) showed a conversion of >99%.

[0082] Subsequently, purified divinylbenzene (4.50 mL, 0.0252 mol) was injected into the ampoule via syringe and the polymerization was continued for 18 h to obtain a dispersion of spherical cross-linked polystyrene@polyisoprene particles. 0.50 mL of methanol was added to the system to terminate the reaction. Finally, the reaction solution was slowly poured into methanol for precipitation. The precipitated product was filtered and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The results were analyzed by nuclear magnetic resonance spectroscopy ( 1 The conversion rate was >99% as determined by H NMR and the products were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM).

[0083] (2) Preparation of hydroxylated cross-linked polystyrene@polyisoprene particles

[0084] First, the cross-linked polystyrene@polyisoprene particles (4.0000 g) and anhydrous toluene (120.0 mL, 104.0 g) prepared above were added to a 250 mL round-bottom flask equipped with a magnetic stirrer and stirred until completely dispersed. Then, trifluoroacetic acid (6.2000 g, 0.0543 mol) was added to the flask under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, 24% w / w sodium methoxide / methanol solution (7.3600 g, 0.0330 mol) was added, and after stirring at room temperature for 16 h, the pH value was adjusted to neutral. Finally, the reaction solution was slowly poured into methanol for precipitation, and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The results were analyzed by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed that the hydroxylation rate was >95%.

[0085] (3) Preparation of cross-linked polystyrene@polyisoprene polyisoprene-g-poly(2-(dimethylamino)ethyl methacrylate) particles

[0086] The designed solid content is 20wt%. First, the hydroxylated cross-linked polystyrene@polyisoprene particles (0.5000g) and anhydrous tetrahydrofuran (30.0mL, 26.6g) prepared above were added to a 100mL round-bottom flask equipped with a magnetic stirrer. Dry high-purity nitrogen was blown into the reaction flask, and a tetrahydrofuran solution of diphenylmethyl potassium (2.85mL, 0.54mmol / mL) was added to obtain a light yellow macroinitiator solution. The measured amount of 2-(dimethylamino)ethyl methacrylate (DMAEMA, 7.10mL, 0.0421mol) monomer was quickly added to the reaction flask, and methanol (1.0mL, 0.0247mol) was added after polymerization for 3h. Finally, the sample was precipitated in n-heptane and dried in a vacuum oven at 45°C for 12h. The reaction was analyzed by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed a conversion of >99%.

[0087] (4) Preparation of cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles

[0088] First, the cross-linked polystyrene@polyisoprene-g-poly 2-(dimethylamino)ethyl methacrylate particles (1.0000 g) and tetrahydrofuran (20.0 mL, 17.7 g) prepared above were added to a 50 mL round-bottom flask equipped with a magnetic stirrer. After thorough dispersion, bromoacetic acid (1.2950 g, 8.60 mmol) was added. The reaction flask was then transferred to a 50°C oil bath and reacted for 24 h. Finally, the product was precipitated in ether and washed several times, and dried in a vacuum oven at 45°C for 12 h to obtain the zwitterionic particle product. The product was characterized by nuclear magnetic resonance spectroscopy ( 1 The zwitterionization degree was >99% as measured by HNMR. The zwitterion particles were spherical particles with an average diameter of 145 nm as measured by DLS and TEM. Figure 1 shown.

[0089] Example 2

[0090] This embodiment provides a method for preparing cross-linked polymethylstyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles, and the specific steps are as follows:

[0091] The solid content in Example 1(1) was changed to 15 wt %, styrene was replaced with p-methylstyrene, 2-(dimethylamino)ethyl methacrylate in Example 1(3) was replaced with 2-(diisopropylamino)ethyl methacrylate, the amount of bromoacetic acid in Example 1(4) was increased by 1 time, the temperature was increased to 60° C., and the other steps were the same as in Example 1, thereby preparing cross-linked poly(p-methylstyrene)@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles.

[0092] Example 3

[0093] This embodiment provides a method for preparing cross-linked polystyrene@polyisoprene-g-poly-4-vinylpyridine sulfobetaine zwitterionic particles, and the specific steps are as follows:

[0094] The 2-(dimethylamino)ethyl methacrylate in Example 1(3) was replaced with 4-vinylpyridine, and the bromoacetic acid in Example 1(4) was replaced with 1,3-propane sultone and the amount was increased by 1 times. The other steps were the same as in Example 1 to prepare cross-linked polystyrene@polyisoprene-g-poly-4-vinylpyridine sulfobetaine zwitterionic particles.

[0095] Example 4

[0096] This embodiment provides a method for preparing cross-linked polymethyl methacrylate@polyisoprene-g-polyacrylamide sulfobetaine zwitterionic particles, and the specific steps are as follows:

[0097] (1) Preparation of cross-linked polymethyl methacrylate@polyisoprene particles

[0098] The designed solid content is 15wt%. First, a 250mL ampoule equipped with a magnetic stirrer is vacuum-baked, and refined tetrahydrofuran (92.5mL, 82.05g) is added sequentially with a syringe thereto. The ampoule is transferred to a -78°C alcohol bath and filled with nitrogen. Subsequently, refined isoprene monomer (9.00mL, 0.0895mol) is added to the ampoule with a syringe, and rapidly metered sec-butyl lithium (0.37mL, 0.48mmol, 1.30mmol / mL) is added as an initiator to initiate isoprene polymerization. After the reaction is carried out for 2.0h, 0.50mL of the reaction solution is taken for characterization. The molecular weight M is measured using gel permeation chromatography (GPC). n =20,300 g / mol, M w / M n =1.06; NMR spectra ( 1 H NMR) showed a conversion of >99%.

[0099] Then, lithium chloride tetrahydrofuran solution (9.71 mL, 0.033 g / mL) and 1,1-diphenylethylene (0.3115 g, 1.92 mmol) were added to the system. After 10 minutes, purified methyl methacrylate (18.30 g, 0.1826 mol) was added to the ampoule. The reaction was continued for 2.0 hours to obtain polyisoprene-b-polymethyl methacrylate block copolymer. 0.50 mL of the reaction solution was terminated with methanol. The molecular weight M was measured by gel permeation chromatography (GPC). n =85,400 g / mol, M w / Mn =1.09; NMR spectrum ( 1 H NMR) showed a conversion of >99%.

[0100] Subsequently, ethylene glycol dimethacrylate (1.0197 g, 0.0051 mol) was injected into the ampoule via a syringe and the polymerization was continued for 1.5 h to obtain a dispersion of spherical cross-linked polymethyl methacrylate@polyisoprene particles. 0.50 mL of methanol was added to the system to terminate the reaction. Finally, the reaction solution was slowly poured into methanol for precipitation. The precipitated product was filtered and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The results were analyzed by nuclear magnetic resonance spectroscopy ( 1 The product was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM).

[0101] (2) Preparation of cross-linked polymethyl methacrylate@hydroxylated polyisoprene particles

[0102] First, the cross-linked polymethyl methacrylate @ polyisoprene particles (4.0000 g) and anhydrous toluene (120.0 mL, 104.0 g) prepared above were added to a 250 mL round-bottom flask equipped with a magnetic stirrer and stirred until completely dispersed. Then, trifluoroacetic acid (6.8200 g, 0.0597 mol) was added to the flask under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, 24% w / w sodium methoxide / methanol solution (8.8320 g, 0.0396 mol) was added, and after stirring at room temperature for 16 h, the pH value was adjusted to neutral. Finally, the reaction solution was slowly poured into methanol for precipitation, and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The results were analyzed by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed that the hydroxylation rate was >95%.

[0103] (3) Preparation of cross-linked polymethyl methacrylate@bromoisobutyl esterified polyisoprene particles

[0104] First, the cross-linked polymethyl methacrylate @ hydroxylated polyisoprene (0.8010 g) and anhydrous dichloromethane (30.0 mL, 0.468 mol) prepared above were added sequentially to a 100 mL round-bottom flask equipped with a magnetic stirrer. After stirring until completely dispersed, triethylamine (0.5025 g, 4.940 mmol) was added. After the oxygen in the flask was replaced with nitrogen, 2-bromoisobutyryl bromide (1.7026 g, 7.395 mmol) was slowly added to the flask in an ice-water bath, and the mixture was reacted at room temperature for 72 h. Finally, the polymer was precipitated with methanol and dried in a vacuum oven at 35 ° C for 12 h. The NMR spectroscopy ( 1 H NMR) showed that the bromoisobutyl esterification rate was >95%.

[0105] (4) Preparation of cross-linked polymethyl methacrylate@polyisoprene-g-poly N-(3-dimethylaminopropyl)methacrylamide particles

[0106] The designed solid content was 50 wt %. First, the cross-linked polymethyl methacrylate@bromoisobutyl esterified polyisoprene particles (0.2306 g), N-(3-dimethylaminopropyl)methacrylamide (26.2 mL, 0.1103 mol), N,N,N′,N′,N″-pentamethyldiethylenetriamine (0.4608 g, 2.650 mmol) and toluene (16.5 mL, 14.6 g) prepared above were added to a 100 mL flask equipped with a magnetic stirrer. The system was placed in a Schlenk flask. Then, the system was subjected to three freeze-pump-thaw cycles to remove dissolved oxygen in the solution. After adding cuprous bromide (0.1913 g, 1.320 mmol) in the third frozen state, the freeze-pump-thaw cycle was performed again. After the system returned to room temperature, nitrogen was introduced into the flask, and the Schlenk flask was placed in an oil bath at 60°C for 24 hours. Finally, the sample was precipitated in n-heptane and dried in a vacuum oven at 45°C for 12 hours.

[0107] (5) Preparation of cross-linked polymethyl methacrylate@polyisoprene-g-polyacrylamide sulfobetaine amphoteric particles

[0108] First, the cross-linked polymethyl methacrylate@polyisoprene-g-poly N-(3-dimethylaminopropyl) methacrylamide particles (1.0000 g) and tetrahydrofuran (20.0 mL, 17.7 g) prepared above were added to a 50 mL round-bottom flask equipped with a magnetic stirrer. After sufficient dispersion, 1,3-propane sultone (2.3112 g, 18.92 mmol) was added. Then, the reaction flask was transferred to a 40 ° C oil bath and reacted for 24 hours. Finally, the product was precipitated in ether and washed several times, and dried in a vacuum oven at 45 ° C for 12 hours to obtain a zwitterionic particle product. The product was characterized by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed that the degree of zwitterionization was >99%. The product was characterized by DLS and TEM.

[0109] Example 5

[0110] This embodiment provides a method for preparing cross-linked polymethyl methacrylate@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles, and the specific steps are as follows:

[0111] The solid content in Example 4(1) was changed to 10 wt %, and the amount of methyl methacrylate was increased by 2 times; N-(3-dimethylaminopropyl)methacrylamide in Example 4(4) was replaced by 2-(dimethylamino)ethyl methacrylate, and 1,3-propane sultone in Example 4(5) was replaced by bromopropionic acid. The other steps were the same as in Example 4, and polymethyl methacrylate@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles were prepared. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that the particles were worm-like particles with an average length of 450 nm and an average width of 30 nm, as shown in FIG. Figure 2 shown.

[0112] Example 6

[0113] This embodiment provides a method for preparing cross-linked polybutyl methacrylate@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles, and the specific steps are as follows:

[0114] The methyl methacrylate in Example 4(1) was replaced by butyl methacrylate, the 1,3-propane sultone in Example 4(5) was replaced by sodium chloroacetate, the reaction temperature was changed to room temperature, the reaction time was changed to 48 h, and the other steps were the same as in Example 4 to prepare cross-linked polybutyl methacrylate@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles.

[0115] Example 7

[0116] This embodiment provides a method for preparing cross-linked poly-α-methylstyrene zwitterionic particles@polybutadiene-g-polymethacrylate carboxybetaine zwitterionic particles, and the specific steps are as follows:

[0117] (1) Preparation of cross-linked poly-α-methylstyrene@polybutadiene particles

[0118] Design solid content is 18wt%.At first, the 500mL ampoule bottle that magnetic stirring bar is housed is carried out vacuum baking, to wherein adding refining normal heptane (240.0mL, 164.2g), tetrahydrofuran (THF) (0.10mL, 1.22mmol) and divinyl (11.19g, 0.225mol is dissolved in 50.0mL normal heptane) with syringe successively, and charge into nitrogen.Subsequently the n-Butyl Lithium (0.30mL, 0.48mmol, 1.60mmol / mL) of metering is added rapidly in the ampoule bottle, reaction is carried out for 24h and can obtain the polybutadiene macroinitiator, gets the 0.50mL reaction solution and stops with methyl alcohol.Record polybutadiene molecular weight M with gel permeation chromatography (GPC). n =52,300 g / mol, M w / M n =1.06; using nuclear magnetic resonance spectroscopy (1 H NMR) showed a conversion of >99%.

[0119] Then, α-methylstyrene monomer (22.6 mL, 0.174 mol) was injected into the ampoule via a syringe and the polymerization was continued for 24 h to obtain polybutadiene-b-polyα-methylstyrene block copolymer. 0.50 mL of the reaction solution was terminated with methanol. The molecular weight M was measured by gel permeation chromatography (GPC). n =210,600 g / mol, M w / M n =1.10; NMR spectra ( 1 H NMR) showed a conversion of >99%.

[0120] Subsequently, purified divinylbenzene (9.00 mL, 0.0504 mol) was injected into the ampoule via a syringe, and the polymerization was continued for 18 h to obtain a dispersion of cross-linked poly-α-methylstyrene@polybutadiene particles. 0.50 mL of methanol was added to the system to terminate the reaction. Finally, the reaction solution was slowly poured into methanol for precipitation, the precipitated product was filtered, and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The results were analyzed by nuclear magnetic resonance spectroscopy ( 1 The product was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM).

[0121] (2) Preparation of cross-linked poly-α-methylstyrene@hydroxylated polybutadiene particles

[0122] First, the cross-linked poly-α-methylstyrene@polybutadiene (12.0000 g) and anhydrous toluene (270.0 mL, 234.0 g) prepared above were added to a 500 mL round-bottom flask equipped with a magnetic stirrer and stirred until completely dispersed. Then, trifluoroacetic acid (10.54 g, 0.0923 mol) was added to the flask under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, 24% w / w sodium methoxide / methanol solution (14.72 g, sodium methoxide 0.0660 mol) was added, and after stirring at room temperature for 16 h, the pH value was adjusted to neutral. Finally, the reaction solution was slowly poured into methanol for precipitation, and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The product was characterized by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed that the hydroxylation rate was >90%.

[0123] (3) Preparation of poly-α-methylstyrene@polybutadiene chain transfer reagent

[0124] First, the cross-linked poly(α-methylstyrene)@hydroxylated polybutadiene (4.0100 g) prepared above was ultrasonically dispersed in a dicyclohexylcarbodiimide (DCC) solution (15.0 mL, 0.46 mol / L, containing 18.48 mmol DCC) for 10 minutes. A 4-cyano-4-(phenylthiocarboylthio)valeric acid (CPADB) solution (7.50 mL, 0.40 mol / L, containing 14.78 mmol CPADB) was added and stirred at room temperature for 30 minutes. Subsequently, a 4-dimethylaminopyridine (DMAP) solution (3.75 mL, 0.44 mol / L, containing 2.46 mmol DMAP) was slowly added dropwise over 30 minutes. The reaction was continued at room temperature for 120 hours. After completion of the reaction, the mixture was centrifuged and washed three times with dichloromethane, tetrahydrofuran, tetrahydrofuran / water (1:1), deionized water, and methanol, respectively. The mixture was then dried in a vacuum oven at 45°C for 12 hours to obtain a dry product. By nuclear magnetic resonance spectroscopy ( 1 H NMR) measured conversion rate> 70%

[0125] (4) Preparation of cross-linked poly-α-methylstyrene@polybutadiene-g-poly-2-(dimethylamino)ethyl methacrylate particles

[0126] The designed solid content is 20wt%. First, the poly-α-methylstyrene@polybutadiene chain transfer reagent (1.0000g) and tetrahydrofuran (50.0mL, 44.3g) prepared above were added to a 100mL round-bottom flask equipped with a magnetic stirrer and stirred until completely dispersed. 2-(Dimethylamino)ethyl methacrylate (10.9mL, 0.0647mol) and azobisisobutyronitrile (0.0354g, 0.216mmol) were added to the reaction bottle and the bottle mouth was sealed with a rubber stopper. Then, after bubbling nitrogen for 30 minutes, the polymerization bottle was placed in a 65°C oil bath for reaction for 12h. Finally, the sample was precipitated in n-heptane and dried in a vacuum oven at 45°C for 12h. The results were analyzed by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed a conversion of >70%.

[0127] (5) Preparation of cross-linked poly-α-methylstyrene@polybutadiene-g-polymethacrylate carboxybetaine zwitterionic particles

[0128] First, the cross-linked poly-α-methylstyrene@polybutadiene-g-poly-2-(dimethylamino)ethyl methacrylate particles (2.0000 g) and tetrahydrofuran (40.0 mL, 35.4 g) prepared above were added to a 100 mL round-bottom flask equipped with a magnetic stirrer. After thorough dispersion, sodium bromoacetate (5.6326 g, 35.00 mmol) was added. Then, the reaction flask was transferred to a 70°C oil bath and reacted for 24 hours. Finally, the product was precipitated in ether and washed several times, and dried in a vacuum oven at 45°C for 12 hours to obtain the zwitterionic particle product. The product was characterized by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed that the degree of zwitterionization was >99%, and the product was characterized by DLS and TEM.

[0129] Example 8

[0130] This embodiment provides a method for preparing cross-linked poly-α-methylstyrene@polybutadiene-g-polyacrylamide sulfobetaine zwitterionic particles, and the specific steps are as follows:

[0131] The 2-(dimethylamino)ethyl methacrylate in Example 7(4) was replaced with N,N-dimethylacrylamide, and the sodium bromoacetate in Example 7(5) was replaced with sodium 2-bromoethanesulfonate. The other steps were the same as those in Example 7 to prepare cross-linked poly-α-methylstyrene@polybutadiene-g-polyacrylamide sulfobetaine zwitterionic particles.

[0132] Example 9

[0133] This embodiment provides a method for preparing cross-linked poly-α-methylstyrene@polybutadiene-g-poly-N-vinylimidazole phosphobetaine zwitterionic particles, and the specific steps are as follows:

[0134] The 2-(dimethylamino)ethyl methacrylate in Example 7(4) was replaced with N-vinylimidazole, and the sodium bromoacetate in Example 7(5) was replaced with glycidyl phosphate. The other steps were the same as in Example 7 to prepare cross-linked poly-α-methylstyrene@polybutadiene-g-poly-N-vinylimidazole phosphobetaine zwitterionic particles.

[0135] Example 10

[0136] This embodiment provides a method for preparing cross-linked poly-m-methylstyrene@polybutadiene-g-polyacrylamide sulfobetaine zwitterionic particles, and the specific steps are as follows:

[0137] Design solid content is 15wt%.At first, the 500mL ampoule bottle that magnetic stirring bar is housed is carried out vacuum baking, to wherein adding refining normal heptane (300.0mL, 205.2g), tetrahydrofuran (THF) (0.20mL, 2.44mmol) and divinyl (12.43g, 0.250mol is dissolved in 50.0mL normal heptane) with syringe successively, and charge into nitrogen.Subsequently the n-Butyl Lithium (1.50mL, 2.40mmol, 1.60mmol / mL) of metering is added rapidly in the ampoule bottle, reaction is carried out for 24h and can obtain the polybutadiene macroinitiator, gets the 0.50mL reaction solution and stops with methyl alcohol.Record polybutadiene molecular weight M with gel permeation chromatography (GPC). n =9,500 g / mol, M w / M n =1.05; using nuclear magnetic resonance spectroscopy ( 1 H NMR) showed a conversion of >99%.

[0138] Then, n-butyl lithium (1.50 mL, 2.40 mmol, 1.60 mmol / mL) was added to the ampoule, and after stirring for 0.5 h, m-methylstyrene monomer (22.6 mL, 0.174 mol) was injected into the ampoule with a syringe, and the polymerization was continued for 24 h to obtain polybutadiene-b-poly-m-methylstyrene / poly-m-methylstyrene block copolymer. 0.50 mL of the reaction solution was terminated with methanol. The molecular weight M was measured by gel permeation chromatography (GPC). n =31,200 g / mol, M w / M n =1.10; NMR spectra ( 1 H NMR) showed a conversion of >99%.

[0139] Subsequently, purified divinylbenzene (9.00 mL, 0.0504 mol) was injected into the ampoule via a syringe and the polymerization was continued for 18 h to obtain a dispersion of cross-linked poly(m-methylstyrene)@polybutadiene particles. 0.50 mL of methanol was added to the system to terminate the reaction. Finally, the reaction solution was slowly poured into methanol for precipitation. The precipitated product was filtered and dried in a vacuum oven at 45 ° C for 12 h to obtain a dry product. The product was characterized by nuclear magnetic resonance spectroscopy ( 1 H NMR) showed that the conversion rate was >99%. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that the particles were spherical with an average diameter of 360 nm.

[0140] Finally, the 2-(dimethylamino)ethyl methacrylate in Example 7(4) was replaced with N-(2-morpholinoethyl)acrylamide, and the sodium bromoacetate in Example 7(5) was replaced with glycidyl phosphate. The other steps were the same as in Example 7 to prepare cross-linked poly(m-methylstyrene)@polybutadiene-g-polyacrylamide sulfobetaine zwitterionic particles.

[0141] Example 11

[0142] This embodiment provides a method for preparing cross-linked poly(p-methoxystyrene)@polybutadiene-g-polyacrylamide) sulfobetaine zwitterionic particles, and the specific steps are as follows:

[0143] The amount of n-butyl lithium added in Example 10(1) was doubled, m-methylstyrene was replaced with p-methoxystyrene, and the other steps were the same as in Example 7 to prepare cross-linked poly(p-methoxystyrene)@polybutadiene-g-polyacrylamide sulfobetaine zwitterionic particles.

[0144] Example 12

[0145] This is a test of the silver loading capacity of the cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles prepared in Example 1:

[0146] As described in Example 1, the particles have a spherical structure, and their average diameter is approximately 145 nm as measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). 0.5000 g of the zwitterionic particles were dissolved in 49.5 g of deionized water to prepare a zwitterionic particle dispersion with a solid content of 1 wt%. Simultaneously, 0.5000 g of silver nitrate was dissolved in 10.0 g of deionized water to prepare a silver nitrate solution with a solid content of 5 wt%. 10.0 g of the zwitterionic particle dispersion was added to a 50 mL round-bottom flask equipped with a magnetic stirrer. 0.54 mL of the silver nitrate solution was added dropwise to the zwitterionic particle dispersion while stirring, and the reaction was continued with stirring for 5 h. Then, 1.60 mL of a hydrazine hydrate solution with a solid content of 1 wt% was added at a rate of 0.05 mL / min, and the reaction was continued with stirring for 2 h to obtain zwitterionic particles loaded with silver particles. The solution was precipitated with ether and centrifuged for purification, then dried in a vacuum oven at 45°C to constant weight to obtain silver-loaded cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles. The zwitterionic particles were then purified and tested by thermogravimetric analysis. The results were as follows: Figure 3 As shown, the calculated load efficiency is 90.8%.

[0147] Load rate calculation formula:

[0148]

[0149] Example 13

[0150] This example is a test of the copper loading capacity of the cross-linked polystyrene@polyisoprene-g-polymethacrylate carboxybetaine zwitterionic particles prepared in Example 1:

[0151] The silver nitrate in Example 12 was replaced with copper chloride, and the other steps were the same as in Example 12. The copper particle loading efficiency was calculated by thermogravimetric analysis and was 92.4%.

[0152] Comparative Example 1

[0153] Cross-linked polymethyl methacrylate@polyisoprene-g-polymethoxypolyethylene glycol monomethacrylate particles were prepared according to the method of Example 4, except that N-(3-dimethylaminopropyl)methacrylamide was replaced with methoxypolyethylene glycol monomethacrylate and step (5) was omitted. The silver loading capacity test procedure was the same as in Example 12.

[0154] in conclusion:

[0155] Because the grafted side chain methoxypolyethylene glycol monomethacrylate lacks a coordinating group, the silver particles precipitate after hydrazine hydrate reduction, and the thermogravimetric curves of the particles before and after loading are similar, indicating that silver loading is not effectively achieved. This demonstrates that the presence of zwitterions is key to achieving metal loading.

[0156] Comparative Example 2

[0157] The cuprous bromide / N,N,N′,N′,N″-pentamethyldiethylenetriamine in Example 4(4) was replaced with azobisisobutyronitrile, the temperature was raised to 70° C., and conventional free radical polymerization was carried out. The other steps were the same as in Example 4.

[0158] in conclusion:

[0159] The poly (N-(3-dimethylaminopropyl)methacrylamide) polymer precipitated as a gel, was non-dispersible in water, and could not be further modified with zwitterions. This demonstrates that the shell conjugate must be covalently bonded to the core polymer; otherwise, the shell and core polymers separate and the composite nanoparticles fail to function.

[0160] The present invention first prepares core-shell polymer particles with a polydiene shell and a cross-linked polystyrene or cross-linked polymethacrylate core through a polymerization-induced self-assembly technique mediated by living anionic polymerization combined with post-polymerization modification. The polydiene shell is then hydrolyzed with trifluoroacetic acid to produce a hydroxylated polydiene. The hydroxyl groups are then converted to potassium alcoholate, isobutyl bromoester (an atom transfer radical polymerization initiator), or a reversible addition-fragmentation chain transfer polymerization agent to initiate controlled / living polymerization of tertiary amine-containing olefinic monomers. Finally, a modification agent is used to convert the tertiary amine groups into zwitterionic groups, producing core-shell particles with a water-soluble zwitterionic polymer shell and a water-insoluble polymer core.

[0161] The zwitterionic particles and their preparation method developed in this invention address the limitations of existing technologies in terms of controllability and functional expansion. The preparation method of this invention offers advantages such as broad applicability and high solids content. The resulting zwitterionic particles exhibit adjustable size, controllable morphology, and stable aqueous dispersion. The zwitterionic particles of this invention can be used for loading nanometal catalysts or extracting heavy metal ions from dilute solutions.

[0162] In the present invention, the particle size can be increased and the morphology can be transformed from spherical to worm-like by increasing the molecular weight ratio of the solvophobic block (such as polystyrene or polymethacrylate) to the solvophilic block (such as polyisoprene). The particle size can also be increased by adding an additional amount of butyl lithium before adding the styrene monomer or methacrylate monomer.

[0163] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A zwitterionic particle, characterized in that: The zwitterionic particles are of a core-shell structure, wherein the shell is a water-soluble zwitterionic polymer and the core is a water-insoluble cross-linked polymer.

2. The zwitterionic particles according to claim 1, characterized in that The zwitterionic particles have a spherical or worm-like structure, and the particle size ranges from 25 nm to 2000 nm.

3. A method for preparing zwitterionic particles according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: Preparation of core-shell polymer particles with a polydiene shell and a cross-linked polystyrene polymer or a cross-linked polymethacrylate polymer as the core using living anionic polymerization-mediated polymerization-induced self-assembly technology; S2: hydrolyzing the polydiene in the upper shell of the core-shell polymer particles with trifluoroacetic acid to prepare a hydroxylated polydiene; S3: using diphenylmethyl potassium to convert the hydroxyl groups on the hydroxylated polydiene block into potassium alcoholate, thereby initiating living anionic polymerization of tertiary amine-containing olefin monomers; or using bromoisobutyryl bromide to convert the hydroxyl groups on the hydroxylated polydiene block into bromoisobutyl ester, thereby initiating atom transfer radical polymerization of tertiary amine-containing olefin monomers; or using 4-cyano-4-(phenylthioformylthio) pentanoic acid to convert the hydroxyl groups on the hydroxylated polydiene block into a chain transfer agent, thereby initiating reversible addition-fragmentation chain transfer polymerization of tertiary amine-containing olefin monomers; thereby providing the shell polymer with tertiary amine groups; S4: using a modification reagent to convert the tertiary amine groups on the shell polymer into zwitterionic groups, thereby preparing zwitterionic particles having a shell of a water-soluble zwitterionic polymer and a core of a water-insoluble cross-linked polymer.

4. The method for preparing zwitterionic particles according to claim 3, wherein: The cross-linked polystyrene polymer in step S1 is any one or more combinations of polystyrene, poly-α-methylstyrene, poly-p-methylstyrene, poly-m-methylstyrene, poly-p-tert-butylstyrene, poly-p-tert-butoxystyrene, poly-1,1-diphenylethylene, poly-p-methoxystyrene, poly-p-trimethylsiloxystyrene, and poly-4-vinylbiphenyl; The cross-linked polymethacrylate polymer in step S1 is any one or more combinations of polymethyl methacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, poly-tert-butyl methacrylate, poly-n-hexyl methacrylate, poly-n-octyl methacrylate, poly-isooctyl methacrylate, poly-dodecyl methacrylate, poly-octadecyl methacrylate, and poly-ferrocenylmethyl methacrylate; The polydiene in step S1 is any one of polyisoprene and polybutadiene or a combination thereof.

5. The method for preparing zwitterionic particles according to claim 3, wherein: In the polymerization-induced self-assembly process of step S1, the solid content of the reaction system is 1 to 50 wt %, the solvent is any one or more combinations of cyclohexane, n-hexane, n-heptane, n-octane, toluene, and tetrahydrofuran, the polymerization temperature is -80 to 100° C., the polymerization time is 0.5 to 48 h, and the cross-linking agent is any one or more combinations of divinylbenzene, ethylene glycol dimethacrylate, pentaerythritol tetramethacrylate, and glycerol trimethacrylate.

6. The method for preparing zwitterionic particles according to claim 3, wherein: The number average molecular weight of the polydiene in step S1 is 1,000 to 100,000 g / mol, and the number average molecular weight of the cross-linked polystyrene polymer or the cross-linked polymethacrylate polymer is 1,000 to 100,000 g / mol.

7. The method for preparing zwitterionic particles according to claim 3, wherein: In the hydrolysis process of step S2, the solid content of the reaction system is 1 to 30 wt %, the solvent is any one or more combinations of tetrahydrofuran, dichloromethane, toluene, methanol, and dioxane, the reaction temperature is 25 to 100° C., the reaction time is 0.5 to 48 h, and the molar ratio of trifluoroacetic acid to the monomer unit on the polydiene is 0.1:1 to 6:

1.

8. The method for preparing zwitterionic particles according to claim 3, wherein: The tertiary amine-containing vinyl monomer in step S3 is any one or more combinations of 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, 2-(diisopropylamino)ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diisopropylamino)ethyl acrylate, N-(3-dimethylaminopropyl)methacrylamide, N-(2-morpholinoethyl)acrylamide, 2-morpholinoethyl methacrylate, 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, and 2-vinyl-1,3-oxazoline; The solid content of the polymerization reaction system in step S3 is 1 to 50 wt%; The shell polymer having tertiary amine groups in step S3 is a polytertiary amine polymer with a number average molecular weight of 1,000 to 100,000 g / mol.

9. The method for preparing zwitterionic particles according to claim 3, wherein: The modification reagent in step S4 is any one or more combinations of bromoacetic acid, bromopropionic acid, sodium bromoacetate, chloroacetic acid, sodium chloroacetate, sodium 2-bromoethanesulfonate, 2-bromoethyl diethyl phosphate, and 1,3-propane sultone; In step S4, the molar ratio of the modification reagent to the tertiary amine group-containing monomer unit on the shell polymer is 0.1:1 to 2:1, the temperature is 25 to 100° C., the reaction time is 0.5 to 48 hours, and the solid content of the reaction system is 1 to 30 wt%.

10. Use of the zwitterionic particles according to any one of claims 1 to 2, characterized in that: The zwitterionic particles are used for loading nano-metal catalysts and extracting metal particles from dilute solutions.

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