Cross-linked AIE polymer nano-particle, preparation thereof and application thereof in detection of aqueous phase nitroaromatic compound
阅读说明：本技术 交联型aie聚合物纳米粒子及其制备和在水相硝基芳香化合物检测中的应用 (Cross-linked AIE polymer nano-particle, preparation thereof and application thereof in detection of aqueous phase nitroaromatic compound ) 是由 曹志海 梁小琴 赵路通 陶萌 秘一芳 于 2021-01-07 设计创作，主要内容包括：本发明公开了交联型AIE聚合物纳米粒子及其制备和在水相硝基芳香化合物检测中的应用。所述交联型AIE聚合物纳米粒子通过如下方法制备：配制乳化剂水溶液,再将AIE单体、常规单乙烯基单体、交联单体和共稳定剂混溶成油相溶液,经预乳化和超声乳化处理制得单体细乳液,在单体液滴内,经自由基聚合反应,将AIE单体通过共聚的方式引入交联的聚合物基体,制得交联型AIE聚合物纳米粒子。本发明提供了所述交联型AIE聚合物纳米粒子作为荧光探针检测水相硝基芳香化合物的应用,其具有灵敏度高、检测下限低、稳定性好等优点。(The invention discloses a cross-linked AIE polymer nano particle, a preparation method thereof and application thereof in detection of a water-phase nitroaromatic compound. The cross-linked AIE polymer nano-particles are prepared by the following method: preparing an emulsifier aqueous solution, mixing AIE monomers, conventional monovinyl monomers, crosslinking monomers and co-stabilizers into an oil phase solution, pre-emulsifying and ultrasonically emulsifying to prepare a monomer miniemulsion, and introducing the AIE monomers into a crosslinked polymer matrix in a monomer droplet in a copolymerization mode through free radical polymerization reaction to prepare the crosslinked AIE polymer nanoparticles. The invention provides application of the cross-linked AIE polymer nano particles as a fluorescent probe to detection of aqueous-phase nitroaromatic compounds, and the cross-linked AIE polymer nano particles have the advantages of high sensitivity, low detection lower limit, good stability and the like.)
1. A crosslinked AIE polymer nanoparticle characterized by: the cross-linked AIE polymer nano-particles are prepared by the following method: preparing an emulsifier aqueous solution, mixing AIE monomers, conventional monovinyl monomers, crosslinking monomers and co-stabilizers into an oil phase solution, pre-emulsifying and ultrasonically emulsifying to prepare a monomer miniemulsion, and introducing the AIE monomers into a crosslinked polymer matrix in a monomer droplet in a copolymerization mode through free radical polymerization reaction to prepare crosslinked AIE polymer nanoparticles;
the AIE monomer is an AIE molecule containing polymerizable vinyl and is selected from at least one of AIE-1 molecules to AIE-17 molecules;
the crosslinking monomer is selected from one or more of the following compounds in combination: acrylate or methacrylate crosslinking monomers shown in formula (I), formula (II) and formula (III), divinylbenzene, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate and pentaerythritol tetramethacrylate;
in the formula (I), R1、R2Each independently is H or CH3，R3Is a C1-C10 aliphatic linear or branched chain alkylene;
in the formula (II), R4、R5Each independently is H or CH3N is 2 or 3;
in the formula (III), R6、R7And R8Each independently is H or CH3，R9Is a fatty straight chain or branched chain alkyl of C1-C3;
the conventional monovinyl monomer is selected from at least one of the following: acrylate or methacrylate monomer shown in formula (IV), vinyl acetate, styrene, hydroxyalkyl methacrylate, hydroxyalkyl acrylate, N-hydroxyalkyl acrylamide, methacrylic acid, acrylic acid, dimethylaminoethyl methacrylate, glycidyl acrylate and glycidyl methacrylate;
in the formula (IV), R10Is H or CH3，R11Is aliphatic straight chain or branched chain alkyl or cyclic alkyl or phenyl or benzyl of C1-C20;
wherein the mass usage of the AIE monomer is 0.01-30% (preferably 0.05-20%) of the total mass usage of the monomers, the mass usage of the conventional monovinyl monomer is 0-98.99% of the total mass usage of the monomers, and the mass usage of the crosslinking monomer at least accounts for 1-99.99% (preferably 5-99.95%) of the total mass usage of the monomers.
2. The cross-linked AIE polymer nanoparticle of claim 1, wherein: the AIE monomer is selected from one or more of AIE-1 to AIE-13.
3. The cross-linked AIE polymer nanoparticle of claim 1, wherein: the crosslinking monomer is at least one selected from divinylbenzene, ethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1, 4-butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and pentaerythritol tetraacrylate.
4. The cross-linked AIE polymer nanoparticle of claim 1, wherein: the conventional monovinyl monomer is selected from at least one of styrene, methyl methacrylate, isobornyl methacrylate and hydroxyethyl methacrylate.
5. A method of preparing the cross-linked AIE polymer nanoparticles of any of claims 1-4, comprising the steps of:
(1) dissolving an emulsifier in deionized water to obtain an emulsifier aqueous solution, wherein the mass consumption of the emulsifier is 0.1-10% of the mass consumption of water; the emulsifier is selected from at least one of the following: anionic, cationic, amphoteric and nonionic emulsifiers;
(2) mixing and dissolving an AIE monomer, a conventional monovinyl monomer, a crosslinking monomer and a co-stabilizer to obtain an oil phase solution, wherein the total mass usage of the monomers is 1-50% of the mass usage of the deionized water in the step (1), the mass usage of the AIE monomer is 0.01-30% of the total mass usage of the monomers, the mass usage of the conventional monovinyl monomer is 0-98.99% of the total mass usage of the monomers, the mass usage of the crosslinking monomer at least accounts for 1-99.99% of the total mass usage of the monomers, and the mass usage of the co-stabilizer is 3-12% of the total mass usage of the monomers;
the co-stabilizer is selected from at least one of the following: aliphatic hydrocarbon of C14-C22, aliphatic alcohol of C14-C22;
(3) adding the emulsifier aqueous solution prepared in the step (1) into the oil phase solution prepared in the step (2), and stirring for pre-emulsification to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and carrying out ultrasonic treatment for 0.5-60 min under the power of 25-950W to prepare a monomer fine emulsion; introducing nitrogen to remove oxygen, and reacting for 0.5-24 h at the temperature of 25-90 ℃ under the protection of nitrogen to prepare cross-linked AIE polymer nano particle emulsion;
and the initiator is introduced by the following means a or b:
in the step (2), adding an oil-soluble initiator into the oil phase solution, wherein the mass usage of the oil-soluble initiator is 0.05-5% of the total mass usage of the monomers;
mode b: in the step (3), a water-soluble initiator is added into the monomer miniemulsion, wherein the mass usage of the water-soluble initiator is 0.05-5% of the total mass usage of the monomers.
6. The method of claim 5, wherein: in the step (1), the anionic emulsifier is selected from at least one of the following: alkyl sulfonate emulsifier R12-SO3M, alkyl sulfate emulsifier R13-OSO3M and alkyl benzene sulfonate emulsifier R14-C6H4-SO3M, wherein R12And R13Each independently is a fatty chain of C10-C20, R14Is a fatty chain of C10-C18, M is Na+Or K+；
The cationic emulsifier is selected from at least one of the following: alkyl trimethyl ammonium halide emulsifier R15N+(CH3)3X–Wherein R is15Is a C12-C20 aliphatic chain, and X is Cl or Br;
the amphoteric emulsifier is selected from at least one of the following: carboxylic acid betaines R16N+(CH3)2CH2COO–Sulfobetaine R17N+(CH3)2CH2CH2SO3 –Or R18N+(CH3)2CH2CH2CH2SO3 –Wherein R is16、R17And R18Each independently is a C12-C18 fatty chain;
the nonionic emulsifier is selected from at least one of the following: OP series emulsifier, O series emulsifier, MOA series emulsifier, Tween series emulsifier and SG series emulsifier.
7. The method of claim 5, wherein: the oil-soluble initiator is selected from at least one of the following: azobisisobutyronitrile, azobisisoheptonitrile, azobisisovaleronitrile, dibenzoyl peroxide, diisopropyl peroxydicarbonate;
the water-soluble initiator is selected from at least one of the following: 2, 2' -azobisisobutylamidine dihydrochloride, azobiscyanovaleric acid, persulfate, an oxidizing agent and a reducing agent; the reducing agent is sulfite, thiosulfate, bisulfite, ascorbate or oxalic acid, and the oxidizing agent is persulfate.
8. The method of claim 5, wherein: in the step (3), the ultrasonic power is 50W-600W, the ultrasonic time is 1 min-30 min, the polymerization temperature is 30-85 ℃, and the reaction time is 1 h-24 h.
9. Use of the cross-linked AIE polymer nanoparticles of any one of claims 1-4 as a fluorescent probe for detecting nitroaromatic compounds in aqueous phase.
10. The use of claim 9, wherein: the nitroaromatic compound is 2,4, 6-trinitrophenol or 2, 4-dinitrotoluene.
(I) technical field
The invention relates to a cross-linked aggregation-induced emission (AIE) polymer nanoparticle, and preparation and application thereof in detection of aqueous-phase nitroaromatic compounds.
(II) background of the invention
Nitroaromatic compounds are common chemicals and widely applied to military and industrial and agricultural construction and production, but due to high toxicity, the nitroaromatic compounds often cause serious pollution to water bodies in the processes of production, use and transportation [ Chemosphere,2009,75,435-41 ]. Therefore, the development of a new material for rapidly and quantitatively detecting the aqueous-phase nitroaromatic compound has important significance for guaranteeing the safety, health and ecological balance of human beings.
At present, the commonly used detection methods for water-phase nitroaromatic compounds mainly include an ion migration method [ Talanta 2003,59,327- & lt333 ], a gas-mass spectrometry combination method [ Talanta 2001,54,427- & lt438 ], a Raman spectrum [ anal. chem.2000,72,5834- & lt5840 ], and the like, and although the detection methods can realize high-sensitivity detection of nitroaromatic compounds, the detection methods have the problems of high-value special equipment, long time consumption, high cost and the like. Fluorescence-based detection methods have the advantages of low consumption, fast response, ultra-convenience and the like, and are receiving more and more attention, wherein fluorescent molecules with AIE characteristics can overcome the aggregation-induced quenching problem of traditional fluorescent molecules, and are ideal nitroaromatic compound fluorescent detection materials [ chem.Commun.2020,56, 2562-; Chin.J.Polym.Sci.2016,35,141-154.
The AIE molecules represented by Tetraphenylethylene (TPE) and its derivatives have been used for the detection of aqueous nitroaromatics by virtue of their high luminous power, good photostability and strong power supply capability. However, hydrophobic AIE small molecules have the problems of poor water dispersibility, low colloidal stability and the like when used, and in contrast, AIE polymer nanoparticles have better water dispersibility and colloidal stability and are more suitable for detecting aqueous-phase nitroaromatic compounds. However, it should be noted that when detecting water-phase nitroaromatic compounds, non-crosslinked AIE polymer nanoparticles are easily swelled by nitroaromatic compounds, resulting in increased size of nanoparticles and even instability of the system, and thus, accurate and quantitative detection of nitroaromatic compounds cannot be achieved [ sens.
Based on the method, the AIE molecules containing vinyl (hereinafter referred to as AIE monomers) are used as fluorescent functional components, and are subjected to copolymerization reaction with conventional monovinyl monomers and crosslinking monomers in a miniemulsion polymerization system to prepare the crosslinking type AIE polymer nanoparticles, and the crosslinking type AIE polymer nanoparticles are used for detecting aqueous phase nitroaromatic compounds.
Disclosure of the invention
It is a first object of the present invention to provide a class of cross-linked AIE polymer nanoparticles.
The second purpose of the invention is to provide a method for preparing cross-linked AIE polymer nano particles based on miniemulsion polymerization technology, wherein the cross-linked AIE polymer nano particles are prepared by introducing AIE monomers into a cross-linked polymer matrix in a copolymerization mode through free radical polymerization reaction in monomer droplets of a miniemulsion polymerization system.
The third purpose of the invention is to provide an application of the cross-linked AIE polymer nano-particles as a fluorescent probe for detecting the water-phase nitroaromatic compound.
In order to achieve the purpose, the invention adopts the technical scheme that:
in a first aspect, the present invention provides a class of cross-linked AIE polymer nanoparticles prepared by the process of: preparing an emulsifier aqueous solution, mixing AIE monomers, conventional monovinyl monomers, crosslinking monomers and co-stabilizers into an oil phase solution, pre-emulsifying and ultrasonically emulsifying to prepare a monomer miniemulsion, and introducing the AIE monomers into a crosslinked polymer matrix in a monomer droplet in a copolymerization mode through free radical polymerization reaction to prepare crosslinked AIE polymer nanoparticles;
the AIE monomer is an AIE molecule containing polymerizable vinyl; the AIE monomer is selected from at least one of AIE-1 to AIE-17 molecules;
the crosslinking monomer is selected from one or more of the following compounds in combination: acrylate or methacrylate crosslinking monomers shown in formula (I), formula (II) and formula (III), divinylbenzene, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate and pentaerythritol tetramethacrylate;
in the formula (I), R1、R2Each independently is H or CH3，R3Is a C1-C10 aliphatic linear or branched chain alkylene;
in the formula (II), R4、R5Each independently isH or CH3N is 2 or 3;
in the formula (III), R6、R7And R8Each independently is H or CH3，R9Is a fatty straight chain or branched chain alkyl of C1-C3;
the conventional monovinyl monomer is selected from at least one of the following: an acrylate or methacrylate monomer represented by formula (IV), vinyl acetate, styrene, hydroxyalkyl methacrylate (the number of carbon atoms in the alkyl group is preferably 1 to 6), hydroxyalkyl acrylate (the number of carbon atoms in the alkyl group is preferably 1 to 6), N-hydroxyalkyl acrylamide (the number of carbon atoms in the alkyl group is preferably 1 to 6), methacrylic acid, acrylic acid, dimethylaminoethyl methacrylate, glycidyl acrylate, and glycidyl methacrylate;
in the formula (IV), R10Is H or CH3，R11Is aliphatic straight chain or branched chain alkyl or cyclic alkyl or phenyl or benzyl of C1-C20;
wherein the mass consumption of the AIE monomer is 0.01-30% of the total mass consumption of the monomer, the mass consumption of the conventional monovinyl monomer is 0-98.99% of the total mass consumption of the monomer, and the mass consumption of the crosslinking monomer at least accounts for 1-99.99% of the total mass consumption of the monomer.
In order to effectively generate charge transfer between the AIE molecules and the nitroaromatic compounds and achieve the aim of effectively quenching fluorescence, an emission group of the AIE monomer has stronger electric supply property; preferably, the AIE monomer is selected from one or more of AIE-1 to AIE-13.
Preferably, the crosslinking monomer is at least one selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1, 4-butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate.
Preferably, the conventional monovinyl monomer is at least one selected from the group consisting of styrene, methyl methacrylate, isobornyl methacrylate, and hydroxyethyl methacrylate.
Preferably, the reaction conditions of the radical polymerization are as follows: under the action of oil-soluble initiator or water-soluble initiator, reacting for 0.5-24 h at 25-95 ℃ under the protection of nitrogen.
Preferably, the Z-average particle diameter of the cross-linked AIE polymer nanoparticles is 30-100 nm.
In a second aspect, the present invention provides a method for preparing cross-linked AIE polymer nanoparticles, the method comprising the steps of:
(1) dissolving an emulsifier in deionized water to obtain an emulsifier aqueous solution, wherein the mass consumption of the emulsifier is 0.1-10% of the mass consumption of water; the emulsifier is selected from at least one of the following: anionic, cationic, amphoteric and nonionic emulsifiers;
(2) mixing and dissolving an AIE monomer, a conventional monovinyl monomer, a crosslinking monomer and a co-stabilizer to obtain an oil phase solution, wherein the total mass usage of the monomers is 1-50% of the mass usage of the deionized water in the step (1), the mass usage of the AIE monomer is 0.01-30% of the total mass usage of the monomers, the mass usage of the conventional monovinyl monomer is 0-98.99% of the total mass usage of the monomers, the mass usage of the crosslinking monomer at least accounts for 1-99.99% of the total mass usage of the monomers, and the mass usage of the co-stabilizer is 3-12% of the total mass usage of the monomers;
the co-stabilizer is selected from at least one of the following: aliphatic hydrocarbon of C14-C22, aliphatic alcohol of C14-C22;
(3) adding the emulsifier aqueous solution prepared in the step (1) into the oil phase solution prepared in the step (2), and stirring for pre-emulsification to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and carrying out ultrasonic treatment for 0.5-60 min under the power of 25-950W to prepare a monomer fine emulsion; introducing nitrogen to remove oxygen, and reacting for 0.5-24 h at the temperature of 25-90 ℃ under the protection of nitrogen to prepare cross-linked AIE polymer nano particle emulsion;
and the initiator is introduced by the following means a or b:
in the step (2), adding an oil-soluble initiator into the oil phase solution, wherein the mass usage of the oil-soluble initiator is 0.05-5% of the total mass usage of the monomers;
mode b: in the step (3), a water-soluble initiator is added into the monomer miniemulsion, wherein the mass usage of the water-soluble initiator is 0.05-5% of the total mass usage of the monomers.
In step (1) of the present invention, the anionic emulsifier may be selected from at least one of the following: alkyl sulfonate emulsifier R12-SO3M, alkyl sulfate emulsifier R13-OSO3M and alkyl benzene sulfonate emulsifier R14-C6H4-SO3M, wherein R12And R13Each independently is a fatty chain of C10-C20, R14Is a fatty chain of C10-C18, M is Na+Or K+。
In step (1) of the present invention, the cationic emulsifier may be selected from at least one of the following: alkyl trimethyl ammonium halide emulsifier R15N+(CH3)3X–Wherein R is15Is a C12-C20 aliphatic chain, and X is Cl or Br.
In step (1) of the present invention, the amphoteric emulsifier may be at least one selected from the group consisting of: carboxylic acid betaines R16N+(CH3)2CH2COO–Sulfobetaine R17N+(CH3)2CH2CH2SO3 –Or R18N+(CH3)2CH2CH2CH2SO3 –Wherein R is16、R17And R18Independently of each other, a fatty chain of C12 to C18.
In step (1) of the present invention, the nonionic emulsifier may be selected from at least one of the following: OP series emulsifier, O series emulsifier, MOA series emulsifier, Tween series emulsifier and SG series emulsifier. Wherein, the OP series emulsifier can be at least one of OP-9, OP-10 and OP-15; the O series emulsifier can be at least one of O-10, O-20, O-30 and O-50; the MOA series emulsifier can be at least one of MOA-7, MOA-9, MOA-15 and MOA-23; the tween series emulsifier can be at least one of tween-20, tween-40, tween-60, tween-80 and tween-85; the SG-series emulsifier may be at least one of SG-40 and SG-100.
In the step (2) of the present invention, in consideration of the light emitting property of the cross-linked AIE polymer nanoparticles and the stability of the polymerization system, the mass usage amount of the AIE monomer is preferably 0.05% to 20% of the total mass usage amount of the monomer.
In the step (2) of the present invention, in consideration of the structural stability of the AIE polymer nanoparticles for detecting water-phase nitroaromatic compounds, the mass usage amount of the crosslinking monomer is preferably 5% to 99.95% of the total mass usage amount of the monomers.
In step (2) of the present invention, the co-stabilizer is preferably a C16-C22 alkane, such as n-hexadecane, in view of the stability of the fine emulsion droplets.
In the initiator addition mode a of the present invention, the oil-soluble initiator is selected from at least one of the following: azobisisobutyronitrile, azobisisoheptonitrile, azobisisovaleronitrile, dibenzoyl peroxide, diisopropyl peroxydicarbonate. Preferably, the oil-soluble initiator is selected from at least one of the following: azobisisobutyronitrile, azobisisoheptonitrile, and azobisisovaleronitrile.
In the initiator addition mode b of the present invention, the water-soluble initiator is selected from at least one of the following: 2, 2' -azobisisobutylamidine dihydrochloride, azobiscyanovaleric acid, persulfate, an oxidizing agent and a reducing agent. Preferably, the reducing agent is a sulfite, thiosulfate, bisulfite, ascorbate, or oxalic acid, more preferably ascorbate; preferably, the oxidant is persulfate, and the persulfate is preferably ammonium persulfate or potassium persulfate.
In the step (3), the ultrasonic power is preferably 50W-600W, the ultrasonic time is preferably 1 min-30 min, the polymerization temperature is preferably 30-85 ℃, and the reaction time is preferably 1 h-24 h.
In a third aspect, the invention provides an application of the cross-linked AIE polymer nanoparticles as a fluorescent probe in detection of water-phase nitroaromatic compounds.
Preferably, the nitroaromatic compound is 2,4, 6-trinitrophenol (PA) or 2, 4-Dinitrotoluene (DNT).
Preferably, the detection is a quantitative detection.
The application specifically comprises the following steps:
(1) taking 20 mu L of cross-linked AIE polymer nanoparticle emulsion in a cuvette, diluting with 2mL of water, shaking up, and placing in a fluorescence spectrometer for scanning a fluorescence spectrum to serve as a blank reference sample;
(2) preparing aqueous solution of nitroaromatic compound with concentration of 0.001 mM-5 mM;
(3) putting 2mL of nitroaromatic compound aqueous solutions with different concentrations in the step (2) into a cuvette, adding the AIE polymer nanoparticle emulsion with the same amount as that in the step (1), shaking up, scanning a fluorescence spectrum in a fluorescence spectrometer, and calculating to obtain a lower limit of detection (LOD);
(4) repeating the processes of the steps (2) and (3) for more than 3 times, fitting to obtain a Stern-Volmer curve according to the corresponding relation between the change of the fluorescence intensity value and the concentration of the nitroaromatic compound, and obtaining a fluorescence quenching constant according to the fitted curve;
(5) taking 2mL of nitroaromatic compound aqueous solution to be detected, putting the nitroaromatic compound aqueous solution into a cuvette, adding the AIE polymer nanoparticle emulsion with the same amount as that in the step (1), shaking up, and scanning a fluorescence spectrum in a fluorescence spectrometer; and (5) calculating by using the fluorescence quenching constant obtained in the step (4) to obtain the concentration of the nitroaromatic compound aqueous solution to be detected.
The aqueous solution of the nitroaromatic compound in the step (1) is an aqueous solution of 2,4, 6-trinitrophenol (PA) or 2, 4-Dinitrotoluene (DNT).
And (3) the cuvette in the step (2) and the step (3) is a quartz cuvette.
The detection lower limit calculation formula in the step (3) is as follows:
LOD＝3σ/k
wherein σ is the standard deviation of fluorescence intensity calculated after the cross-linked AIE polymer nanoparticle aqueous dispersion liquid in the step (1) is scanned for 11 times; and k is the slope of a fitted straight line of the corresponding relation between the fluorescence intensity and the concentration of the nitroaromatic compound in a low concentration range.
The Stern-Volmer equation formula in the step (4) is as follows:
I0/I＝1+KSV[Q]
wherein, KSVIs the Stern-Volmer constant, i.e., the fluorescence quenching constant (M)-1),[Q]Is the concentration of nitroaromatic compound, I0The initial fluorescence intensity of AIE polymer nanoparticle emulsion without nitroaromatic compound is shown in the specification, wherein I is the concentration of the nitroaromatic compound added as [ Q ]]The fluorescence intensity of the aqueous dispersion of AIE polymer nanoparticles.
Compared with the prior art, the invention has the beneficial effects that:
(1) in a miniemulsion polymerization system, a certain amount of crosslinking monomers are added to construct a crosslinking type polymer network structure, AIE monomers are utilized to participate in copolymerization reaction, and AIE components are introduced into a crosslinking polymer matrix in a chemical crosslinking mode, so that the crosslinking type AIE polymer nanoparticles are efficiently and simply prepared. The method has the characteristics of environmental protection due to the water-based system of miniemulsion polymerization.
(2) The cross-linked AIE polymer nano particles and the nitroaromatic compound can generate charge transfer, so that energy is dissipated in a non-radiation mode, fluorescence is weakened or quenched, and the aim of qualitatively and quantitatively detecting the nitroaromatic compound can be fulfilled by monitoring the change of fluorescence intensity. Moreover, due to the characteristics of small particle size and large specific surface area of the AIE polymer nanoparticles, the AIE polymer nanoparticles can quickly capture nitroaromatic compound molecules and have the advantages of high sensitivity, low detection lower limit and the like. In addition, the nano particles have a cross-linked polymer network structure and excellent solvent resistance, and the morphological structure of the nano particles is not affected even in the presence of a high-concentration nitroaromatic compound, so that the stability is good. The cross-linked AIE polymer nano-particles prepared by the invention have important application value in the detection of aqueous phase nitroaromatic compounds.
(IV) description of the drawings
FIG. 1 is a transmission electron micrograph of crosslinked AIE polymer nanoparticles prepared in example 1.
FIG. 2 shows fluorescence spectra of cross-linked AIE polymer nanoparticles prepared in example 1 in the presence of DNT at various concentrations.
(V) detailed description of the preferred embodiments
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:
example 1:
weighing 0.075g of emulsifier sodium dodecyl sulfate and 0.1g of tween-20, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.0005g of AIE-13 molecule, and dissolving in a mixed solution of 0.04g of n-hexadecane and 0.5g of divinylbenzene to obtain an oil phase solution; adding the emulsifier aqueous solution into the oil phase solution, and stirring and pre-emulsifying to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and performing ultrasonic treatment for 9min by using ultrasonic waves with the power of 400W to prepare stable monomer fine emulsion; and adding 0.025g of potassium persulfate into the monomer miniemulsion, introducing nitrogen to remove oxygen, raising the temperature to 70 ℃, and reacting for 5 hours under the protection of nitrogen to obtain the AIE polymer nanoparticle emulsion.
The Z-average particle diameter of the cross-linked AIE polymer nanoparticles measured by a dynamic light scattering nanometer particle size analyzer is 50nm, and the PDI is 0.079. The gel fraction of the AIE polymer nanoparticles was determined to be 100% by extraction, indicating that the AIE polymer nanoparticles produced have a highly crosslinked structure.
Sequentially taking 2mLDNT aqueous solution (the concentration is gradually increased from 0-0.5 mM) into a quartz cuvette, adding 20 mu LAIE polymer nanoparticle emulsion, shaking up, and keeping the Z average particle diameter of the AIE polymer nanoparticles at 50nm in the presence of DNT (deoxyribose nucleic acid) with different concentrations measured by a dynamic light scattering nanometer particle size analyzer, thereby indicating that the prepared cross-linked AIE polymer nanoparticles have good colloidal stability and structural stability.
Scanning the fluorescence spectrum of the solution by a fluorescence spectrometer, and calculatingThe lower detection limit of the prepared cross-linked AIE polymer nanoparticles is 2.89ppm, a Stern-Volmer curve is obtained by fitting according to the corresponding relation between the change of the fluorescence intensity value and the DNT concentration, the fitting index of the curve is 0.998, and K is used for detecting DNT solution in an aqueous phaseSVIs 5.24X 103M-1The cross-linked AIE polymer nanoparticles have the capability of accurately and quantitatively detecting the aqueous-phase nitroaromatic compounds.
Comparative example 1:
weighing 0.075g of emulsifier sodium dodecyl sulfate and 0.1g of tween-20, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.0005g of AIE-13 molecule, and dissolving in a mixed solution of 0.04g of n-hexadecane, 0.3g of styrene and 0.2g of butyl acrylate to obtain an oil phase solution; AIE polymer nanoparticles were prepared using the same preparation conditions as in example 1.
The Z-average particle diameter of the AIE polymer nanoparticles was 52nm and the PDI was 0.115 as measured by a dynamic light scattering nano-particle sizer. The gel fraction of the AIE polymer nanoparticles measured by an extraction method is 1%, which indicates that the prepared AIE polymer nanoparticles only form a very light cross-linking structure due to butyl acrylate self-crosslinking.
The DNT aqueous solution is tested by the same technical scheme as in example 1, and the Z average particle size of the AIE polymer nanoparticles is increased along with the increase of the DNT concentration, and after the DNT concentration reaches 0.25mM, the particle size of the nanoparticles is in multimodal distribution, and the fitting index of the Stern-Volmer curve is only 0.905. The AIE polymer nanoparticles are free of solvent resistance, and the nanoparticles have poor structural stability in the presence of high-concentration nitroaromatic compounds, so that the detection accuracy of the nitroaromatic compounds is further reduced.
Example 2:
weighing 0.15g of emulsifier sodium dodecyl benzene sulfonate, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.003g of AIE-1 molecule and 0.03g of azodiisoheptanonitrile, and dissolving in a mixed solution of 0.2g of n-hexadecane, 1.75g of ethylene glycol dimethacrylate and 0.75g of styrene to obtain an oil phase solution; adding the emulsifier aqueous solution into the oil phase solution, and stirring and pre-emulsifying to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and performing ultrasonic treatment for 15min by using ultrasonic waves with the power of 200W to prepare stable monomer fine emulsion; introducing nitrogen to remove oxygen, heating to 65 ℃, and reacting for 10 hours under the protection of nitrogen to prepare the AIE polymer nanoparticle emulsion.
The Z-average particle diameter of the AIE polymer nanoparticles measured by a dynamic light scattering nanometer particle size analyzer is 70nm, and the PDI is 0.091. The gel fraction of the AIE polymer nanoparticles measured by an extraction method was 98%, indicating that the prepared AIE polymer nanoparticles have a highly crosslinked structure. The cross-linked AIE polymer nano-particle is used for detecting a PA aqueous solution, the lower detection limit is 1.52ppm, the fitting index of the obtained Stern-Volmer curve is 0.997, and K is used for detecting the PA solution in the aqueous phaseSV＝2.34×104M-1。
Example 3:
weighing 0.06g of emulsifier cetyl trimethyl ammonium bromide, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.004g of AIE-2 molecule and 0.04g of azodiisobutyronitrile, and dissolving in a mixed solution of 0.12g of n-hexadecane, 1g of neopentyl glycol dimethacrylate and 1g of methyl methacrylate to obtain an oil phase solution; adding the emulsifier aqueous solution into the oil phase solution, and stirring and pre-emulsifying to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and performing ultrasonic treatment for 12min by using ultrasonic waves with power of 380W to prepare stable monomer fine emulsion; introducing nitrogen to remove oxygen, heating to 65 ℃, and reacting for 10 hours under the protection of nitrogen to prepare the AIE polymer nanoparticle emulsion.
The Z-average particle diameter of the AIE polymer nano particles measured by a dynamic light scattering nano particle size meter is 80nm, and the PDI is 0.051. The gel fraction of the AIE polymer nanoparticles measured by an extraction method was 96%, indicating that the prepared AIE polymer nanoparticles have a highly crosslinked structure.
The cross-linked AIE polymer nano-particle is used for detecting a PA aqueous solution, the lower detection limit is 1.63ppm, the fitting index of the obtained Stern-Volmer curve is 0.998, and K is used for detecting the PA solution in the aqueous phaseSV＝2.21×104M-1。
Example 4:
weighing 0.12g of emulsifier dodecyl dimethyl sulfopropyl betaine, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.002g of AIE-5 molecules and 0.07g of azodiisovaleronitrile, and dissolving in a mixed solution of 0.15g of n-hexadecane, 1g of trimethylolpropane trimethacrylate, 0.5g of isobornyl methacrylate and 0.6g of hydroxyethyl methacrylate to obtain an oil phase solution; adding the emulsifier aqueous solution into the oil phase solution, and stirring and pre-emulsifying to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and performing ultrasonic treatment for 5min by using ultrasonic waves with the power of 600W to prepare stable monomer fine emulsion; introducing nitrogen to remove oxygen, heating to 65 ℃, and reacting for 3 hours under the protection of nitrogen to prepare the AIE polymer nanoparticle emulsion.
The Z-average particle diameter of the cross-linked AIE polymer nanoparticles measured by a dynamic light scattering nanometer particle sizer is 75nm, and the PDI is 0.084. The gel fraction of the AIE polymer nanoparticles was 94% by extraction, indicating that the AIE polymer nanoparticles produced had a highly crosslinked structure.
The cross-linked AIE polymer nano-particle is used for detecting DNT aqueous solution, the lower detection limit is 3.23ppm, the fitting index of the obtained Stern-Volmer curve is 0.997, and K is used for detecting DNT aqueous solution in aqueous phaseSV＝4.76×103M-1。
Example 5:
weighing 0.18g of emulsifier sodium dodecyl sulfate, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.016g of AIE-9 molecule, and dissolving in a mixed solution of 0.28g of n-hexadecane, 0.8g of pentaerythritol tetraacrylate and 1.9g of styrene to obtain an oil phase solution; adding the emulsifier aqueous solution into the oil phase solution, and stirring and pre-emulsifying to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and performing ultrasonic treatment for 10min by using ultrasonic waves with the power of 500W to prepare stable monomer fine emulsion; adding 0.1g of potassium persulfate and 0.25g of sodium ascorbate into the monomer miniemulsion, introducing nitrogen to remove oxygen, heating to 40 ℃, and reacting for 5 hours under the protection of nitrogen to obtain the AIE polymer nanoparticle emulsion.
The Z-average particle diameter of the cross-linked AIE polymer nanoparticles measured by a dynamic light scattering nanometer particle size analyzer is 45nm, and the PDI is 0.071. The gel fraction of the AIE polymer nanoparticles was 91% by extraction, indicating that the AIE polymer nanoparticles produced had a highly crosslinked structure.
The cross-linked AIE polymer nano-particle is used for detecting DNT aqueous solution, the lower detection limit is 2.97ppm, the fitting index of the obtained Stern-Volmer curve is 0.997, and K is used for detecting DNT aqueous solution in aqueous phaseSV＝5.13×103M-1。
Example 6:
weighing 0.05g of sodium dodecyl sulfate and 0.05g of tween-20, and dissolving in 12.5g of deionized water to obtain an emulsifier aqueous solution; weighing 0.025g of AIE-10 molecule, and dissolving in a mixed solution of 0.06g of n-hexadecane, 0.4g of trimethylolpropane triacrylate, 0.2g of 1, 4-butanediol dimethacrylate and 0.3g of methyl methacrylate to obtain an oil phase solution; adding the emulsifier aqueous solution into the oil phase solution, and stirring and pre-emulsifying to obtain a coarse emulsion; placing the container filled with the coarse emulsion in an ice-water bath, and performing ultrasonic treatment for 8min by using ultrasonic waves with the power of 450W to prepare stable monomer fine emulsion; and adding 0.01g of ammonium persulfate into the monomer miniemulsion, introducing nitrogen to remove oxygen, raising the temperature to 70 ℃, and reacting for 6 hours under the protection of nitrogen to obtain the AIE polymer nanoparticle emulsion.
The Z-average particle diameter of the cross-linked AIE polymer nanoparticles measured by a dynamic light scattering nanometer particle size analyzer is 95nm, and the PDI is 0.095. The gel fraction of the AIE polymer nanoparticles measured by an extraction method was 98%, indicating that the prepared AIE polymer nanoparticles have a highly crosslinked structure.
The cross-linked AIE polymer nano-particle is used for detecting DNT aqueous solution, the lower detection limit is 3.63ppm, the fitting index of the obtained Stern-Volmer curve is 0.998, and K is used for detecting DNT aqueous solution in aqueous phaseSV＝3.98×103M-1。
The above-described embodiments of the invention are intended to be illustrative of the invention and are not to be construed as limiting the invention, and any variations that fall within the meaning and scope of the invention equivalent to the claims are intended to be embraced therein.
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