Fluorescent polyethylene glycol terephthalate nanoparticles and preparation method thereof
Polyethylene terephthalate nanoparticles were prepared by nanoprecipitation and swelling methods, which solved the problems of complex operation and fluorescence quenching in traditional methods and achieved uniform particle size distribution and stable luminescence.
Patent Information
- Application Number
- CN202511030126.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-09-12
AI Technical Summary
Existing technologies make it difficult to efficiently prepare polyethylene terephthalate nanoparticles, and traditional fluorescent dyes are easily quenched at high concentrations, affecting their application in the environment.
Polyethylene terephthalate nanoparticles were prepared by nanoprecipitation method combined with swelling method by controlling solvent concentration and reaction conditions. Tetraphenylethylene fluorescent dye was then incorporated into the prepared nanoparticles to form nanoparticles with aggregation-induced emission properties.
The prepared nanoparticles have uniform particle size distribution and good dispersibility, avoid fluorescence quenching, maintain good luminescence performance, and are suitable for a variety of environmental conditions.
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Figure CN120623518A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of nanoparticle preparation, in particular to fluorescent polyethylene terephthalate nanoparticles and a preparation method thereof. Background Art
[0002] Plastics are widely used in various fields around the world due to their durability, lightness, strength, affordability, thermal insulation, and electrical insulation. While plastic products provide convenience for human production and daily life, they also place pressure on the environment. Due to the widespread distribution and difficult degradation of plastic products, plastic pollution in the environment is becoming increasingly prominent, especially micro- and nano-plastic pollution, which has become a global focus. Micro- and nano-plastics are difficult to separate from environmental samples, and related research mainly relies on plastic models. Traditional chemical synthesis methods are used to prepare micro- and nano-plastic models. Among them, polystyrene sphere models can reflect the particle size and material of micro- and nano-plastics to a certain extent, but their environmental relevance is insufficient. There are many types of plastics in the environment, including polyethylene, polyvinyl chloride, polypropylene, polyethylene terephthalate, and polystyrene. Among them, polystyrene only accounts for approximately 7% of the total plastic production and has significant differences from other types of plastic particles in terms of density and interaction patterns with endogenous biomolecules.
[0003] Against the backdrop of increasingly serious plastic pollution, polyethylene terephthalate, a thermoplastic polymer with a very high annual global production, urgently needs innovation in the preparation technology of its nanoparticles. Existing preparation methods, such as laser ablation, can produce nanoparticles, but they face problems such as complex operation, low yield and changes in chemical properties, which limit their practical application. Nanoprecipitation has the advantages of simplicity, low cost and strong controllability, and is widely used in the preparation of nanomaterials. However, when preparing polyethylene terephthalate nanoparticles using traditional nanoprecipitation methods, it is often difficult to achieve the required particle size distribution and surface characteristics, resulting in insufficient stability of the particles in the environment, affecting their performance in practical applications.
[0004] Traditional organic fluorescent dyes typically exhibit excellent luminescence properties in dilute solutions. However, when these dyes are in high-concentration solutions or solid states, their luminescence efficiency decreases significantly, a phenomenon known as aggregation-induced quenching (ACQ). The primary cause of ACQ is: enhanced intermolecular interactions: At high concentrations, the distance between fluorescent molecules decreases, leading to enhanced short-range interactions such as π-π stacking. These interactions promote nonradiative transition pathways, causing energy to be dissipated as heat rather than emitted as light. Increased nonradiative energy transfer: As the distance between fluorescent molecules decreases, intermolecular energy transfer becomes easier, resulting in nonradiative energy loss from the excited state, thereby reducing the observed luminescence intensity. Restricted intramolecular motion: In the solid or aggregated state, the rotational and vibrational motions of fluorescent molecules are restricted, which can also increase the probability of nonradiative transitions, leading to fluorescence quenching.
[0005] Therefore, developing a specific nanoparticle production method that maintains the chemical stability of polyethylene terephthalate nanoparticles while simplifying the preparation process and facilitating large-scale production, while also imparting stable luminescence, has become a key challenge for researchers. This will not only enrich research models for micro- and nanoplastics but also contribute to a deeper understanding of the environmental impact of plastic pollution and provide a scientific basis for plastic waste management. Summary of the Invention
[0006] In view of this, the present invention provides fluorescent polyethylene terephthalate nanoparticles and a preparation method thereof, which solves the problems of complex operation, low yield and unsatisfactory particle size distribution existing in traditional nanoparticle preparation methods, and also solves the problem of easy quenching of traditional organic fluorescent aggregation.
[0007] In order to achieve the above object, the present invention adopts the following technical solutions:
[0008] A method for preparing fluorescent polyethylene terephthalate nanoparticles comprises the following steps:
[0009] 1) crushing and alkali-washing a raw material containing polyethylene terephthalate to obtain polyethylene terephthalate particles;
[0010] 2) mixing the polyethylene terephthalate particles with an organic solvent to obtain a mixed solution, then mixing the mixed solution with a poor solvent for the polyethylene terephthalate particles, and filtering to obtain polyethylene terephthalate nanoparticles;
[0011] 3) mixing polyethylene terephthalate nanoparticles with Tween-20 to obtain a nanoparticle dispersion; subjecting the nanoparticle dispersion to a swelling reaction with a tetraphenylethylene solution to obtain fluorescent polyethylene terephthalate nanoparticles.
[0012] Preferably, the raw material containing polyethylene terephthalate includes polyethylene terephthalate plastic bottles.
[0013] Preferably, the particle size after crushing in step 1) is 250-300 mesh;
[0014] The alkaline solution for alkali washing includes one or more of sodium hydroxide solution, potassium hydroxide solution and ammonia water; the molar concentration of the alkaline solution is 0.1 to 5 mol / L;
[0015] The alkali washing time is 30 to 60 minutes.
[0016] Preferably, the volume ratio of the mixed solution to the polyethylene terephthalate particle poor solvent in step 2) is 1:10-15;
[0017] The particle size of the polyethylene terephthalate nanoparticles obtained after the filtration is ≤0.45 μm.
[0018] Preferably, the mass volume ratio of polyethylene terephthalate particles to organic solvent in the mixed solution in step 2) is 0.025-0.1 g:10 mL;
[0019] The organic solvent in the mixed solution includes one or more of hexafluoroisopropanol, trifluoroacetic acid, chlorophenol, hydrofluoric acid, dimethylformamide, dimethyl sulfoxide and thionyl chloride;
[0020] The poor solvent for polyethylene terephthalate particles includes water or an aqueous solution of sodium lauryl sulfate;
[0021] The mass concentration of the sodium lauryl sulfate aqueous solution is 0.05 mg / mL.
[0022] Preferably, the mixed solution in step 2) is mixed with the polyethylene terephthalate particle poor solvent by dropwise adding the mixed solution into the polyethylene terephthalate particle poor solvent;
[0023] The dropping speed is 1 to 5 mL / min.
[0024] Preferably, the mass volume ratio of the nanoparticle dispersion to the tetraphenylethylene solution in step 3) is 0.02-0.1 g: 1-2 mL;
[0025] Before the swelling reaction, the tetraphenylethylene solution is added dropwise to the nanoparticle dispersion;
[0026] The dropping speed is 2 to 5 drops / min.
[0027] Preferably, the mass ratio of polyethylene terephthalate nanoparticles to Tween-20 in the nanoparticle dispersion in step 3) is 10:1-6;
[0028] The mass volume ratio of tetraphenylethylene to solvent in the tetraphenylethylene solution is 1 mg: 1-2 mL;
[0029] The solvent in the tetraphenylethylene solution includes one or more of tetrahydrofuran, acetone, dichloromethane and N,N-dimethylformamide.
[0030] Preferably, the temperature of the swelling reaction in step 3) is 30-50° C., the swelling reaction time is 2-4 h, and the stirring rate of the swelling reaction is 300-600 rpm.
[0031] Another object of the present invention is to provide fluorescent polyethylene terephthalate nanoparticles prepared by the above preparation method.
[0032] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:
[0033] Compared to traditional laser ablation methods, the nanoprecipitation method provided by the present invention is simple to operate, low in cost, and high in yield. The prepared polyethylene terephthalate nanoparticles are spherical and well dispersed. The high temperatures generated during laser ablation may cause thermal degradation or chemical modification of the polyethylene terephthalate molecular structure, such as dehydration, carbonization, or other side reactions, thereby changing the chemical composition of the final nanoparticles. In contrast, the nanoprecipitation method induces the formation of nanoparticles by controlling the solubility of the polymer in the solution. This method generally involves dissolving the polymer in a good solvent and then slowly adding the solution to another poor solvent to induce the precipitation of the polymer and form nanoscale particles (the organic solvent in step 2 of the present invention is a good solvent, and the mixed solution forms nanoscale particles after mixing with the poor solvent for polyethylene terephthalate particles). The nanoprecipitation process is usually carried out under relatively mild conditions, avoiding high temperatures or high pressures, reducing damage to the polyethylene terephthalate molecular structure, and maintaining the original chemical properties of the material. Secondly, nanoprecipitation methods typically use non-toxic solvents, reducing environmental impact and aligning with the concept of sustainable development. By adjusting precipitation conditions (such as solvent concentration and reaction time), the particle size and shape of the nanoparticles can be precisely controlled, improving product consistency. The prepared nanoparticles exhibit good dispersibility and good physicochemical stability under ambient conditions, reducing sedimentation and aggregation.
[0034] By incorporating tetraphenylethylene fluorescent dyes with aggregation-induced emission into polyethylene terephthalate nanoparticles via a swelling method, they produced AIE-type polymer nanoparticles with excellent luminescence properties. Because AIE molecules are restricted in their intermolecular rotation when aggregated, this prevents fluorescence leakage and quenching within the polymer, reduces non-radiative transitions, and thus enhances fluorescence emission. The swelling method exploits this property and effectively avoids fluorescence quenching by controlling the aggregation state of the molecules, ensuring stable luminescence of the nanoplastic in a variety of environments and overcoming the drawback of traditional organic fluorescent materials that are susceptible to quenching due to aggregation. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0036] Figure 1 This is a SEM image of the fluorescent polyethylene terephthalate nanoparticles prepared in Example 1 of the present invention;
[0037] Figure 2 FTIR image of the fluorescent polyethylene terephthalate nanoparticles prepared in Example 1 of the present invention;
[0038] Figure 3 This is a fluorescence spectrum of the fluorescent polyethylene terephthalate nanoparticles prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0039] The present invention provides a method for preparing fluorescent polyethylene terephthalate nanoparticles, comprising the following steps:
[0040] 1) crushing and alkali-washing a raw material containing polyethylene terephthalate to obtain polyethylene terephthalate particles;
[0041] 2) mixing the polyethylene terephthalate particles with an organic solvent to obtain a mixed solution, then mixing the mixed solution with a poor solvent for the polyethylene terephthalate particles, and filtering to obtain polyethylene terephthalate nanoparticles;
[0042] 3) mixing polyethylene terephthalate nanoparticles with Tween-20 to obtain a nanoparticle dispersion; subjecting the nanoparticle dispersion to a swelling reaction with a tetraphenylethylene solution to obtain fluorescent polyethylene terephthalate nanoparticles.
[0043] In the present invention, the raw material containing polyethylene terephthalate includes polyethylene terephthalate plastic bottles.
[0044] In the present invention, the particle size after crushing in step 1) is 250-300 mesh, specifically 255 mesh, 260 mesh, 265 mesh, 270 mesh, 275 mesh, 280 mesh, 285 mesh, 290 mesh, and 295 mesh.
[0045] In the present invention, the alkaline solution for alkali washing includes one or more of sodium hydroxide solution, potassium hydroxide solution and ammonia water; the molar concentration of the alkaline solution is 0.1 to 5 mol / L, specifically 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, and 4.5 mol / L.
[0046] In the present invention, the alkali washing time is 30 to 60 minutes, specifically 35 minutes, 40 minutes, 45 minutes, 50 minutes, or 55 minutes.
[0047] In the present invention, the volume ratio of the mixed solution in step 2) to the poor solvent for polyethylene terephthalate particles is 1:10-15, preferably 1:11-14, and more preferably 1:12-13.
[0048] In the present invention, the particle size of the polyethylene terephthalate nanoparticles obtained after filtration is ≤0.45 μm, and the filtration is preferably performed using a filter with a pore size of 0.45 μm.
[0049] In the present invention, the mass volume ratio of the polyethylene terephthalate particles to the organic solvent in the mixed solution in step 2) is 0.025-0.1 g:10 mL, preferably 0.05-0.075 g:10 mL, and more preferably 0.06 g:10 mL.
[0050] In the present invention, the organic solvent in the mixed solution includes one or more of hexafluoroisopropanol, trifluoroacetic acid, chlorophenol, hydrofluoric acid, dimethylformamide, dimethyl sulfoxide and thionyl chloride.
[0051] In the present invention, the poor solvent for polyethylene terephthalate particles includes water or an aqueous solution of sodium lauryl sulfate.
[0052] In the present invention, the mass concentration of the sodium lauryl sulfate aqueous solution is 0.05 mg / mL.
[0053] In the present invention, the mixing of the mixed solution and the poor solvent for polyethylene terephthalate particles in step 2) is performed by dropwise adding the mixed solution into the poor solvent for polyethylene terephthalate particles.
[0054] In the present invention, the dropping speed is 1 to 5 mL / min, specifically 1.5 mL / min, 2 mL / min, 2.5 mL / min, 3 mL / min, 3.5 mL / min, 4 mL / min, and 4.5 mL / min.
[0055] In the present invention, sodium lauryl sulfate molecules are anchored to the surface of the nanoplastic via their hydrophobic ends, forming a monolayer adsorption film. This adsorption film effectively inhibits particle aggregation through steric hindrance and electrostatic stabilization, thereby ensuring that the nanoplastic maintains good dispersion in the solution.
[0056] In the present invention, the mass volume ratio of the nanoparticle dispersion to the tetraphenylethylene solution in step 3) is 0.02-0.1 g:1-2 mL, preferably 0.05-0.1:1.5-2, further preferably 0.08-0.1:1.8-2 mL, and further preferably 0.1:2 mL.
[0057] In the present invention, before the swelling reaction, a tetraphenylethylene solution is added dropwise to the nanoparticle dispersion;
[0058] In the present invention, the dropping speed is 2 to 5 drops / min, specifically 2 drops / min, 3 drops / min, 4 drops / min, or 5 drops / min.
[0059] In the present invention, the mass ratio of polyethylene terephthalate nanoparticles to Tween-20 in the nanoparticle dispersion in step 3) is 10:1-6, preferably 10:3-5, more preferably 10:3.5-4.5, and further preferably 10:4.
[0060] In the present invention, the mass of Tween-20 is preferably 0.01 to 0.03 g.
[0061] In the present invention, the mass volume ratio of tetraphenylethylene to solvent in the tetraphenylethylene solution is 1 mg:1-2 mL, preferably 1 mg:1.2-1.6 mL, and more preferably 1 mg:1.5 mL.
[0062] In the present invention, the solvent in the tetraphenylethylene solution includes one or more of tetrahydrofuran, acetone, dichloromethane and N,N-dimethylformamide.
[0063] In the present invention, the temperature of the swelling reaction in step 3) is 30-50°C, specifically 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, and 48°C; the swelling reaction time is 2-4h, specifically 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h, and 3.8h; the stirring rate of the swelling reaction is 300-600rpm, specifically 320rpm, 350rpm, 380rpm, 400rpm, 420rpm, 450rpm, 480rpm, 500rpm, 520rpm, 550rpm, and 580rpm.
[0064] The present invention also provides fluorescent polyethylene terephthalate nanoparticles prepared by the above preparation method.
[0065] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0066] Example 1
[0067] The polyethylene terephthalate (PET) used to produce the nanoparticles was obtained from soft drink bottles. The bottoms of the bottles were scratched with a hacksaw blade to obtain fine debris, which was then screened to obtain particles with a size of 250-300 mesh. One gram of the crushed PET particles was weighed and soaked in 100 mL of 0.5 mol / L sodium hydroxide solution for 30 minutes. After the alkaline wash, the particles were rinsed with copious amounts of deionized water until the rinse water was neutral, and then dried under vacuum at 80°C.
[0068] 0.1 g of polyethylene terephthalate was dissolved in 10 mL of hexafluoroisopropanol for 16 h at a dissolution temperature of 25 ° C and a rotation speed of 800 rpm. Use a syringe pump to add the polyethylene terephthalate solution to 100 mL of a 0.05 mg / mL sodium lauryl sulfate aqueous solution at room temperature at 5 mL / min. After the addition is completed at room temperature, stirring is continued for 2 h. In order to remove larger particles, the solution is filtered through a 0.45 μm nylon syringe filter. The solution is transferred to a 250 mL round-bottom flask and vacuum rotary evaporated to remove residual hexafluoroisopropanol. After reducing the volume in the round-bottom flask, 60 mL of ultrapure deionized water is added and subjected to a second rotary evaporation to obtain polyethylene terephthalate nanoparticles. The temperature of the rotary evaporator is 55 ° C and the vacuum degree is 0.04 MPa;
[0069] Take 0.1g of polyethylene terephthalate nanoparticles and add them to an aqueous solution containing 0.03g of Tween-20. Use an ultrasonic cleaner with a power of 500W to treat the mixture for 20 minutes to ensure uniform dispersion. Dissolve 1mg of tetraphenylethylene (TPE) in 1mL of tetrahydrofuran and add it to the nanoparticle dispersion at a rate of 2 drops / s. Maintain the temperature at 35°C and carry out the swelling reaction at a speed of 300rpm for 2 hours. After the swelling reaction is completed, remove the swelling agent and wash with ethanol-water solution. The washing process continues until the presence of tetraphenylethylene is no longer detected in the centrifuged supernatant using a UV spectrophotometer. Finally, fluorescently labeled nanoparticles - fluorescent polyethylene terephthalate nanoparticles (TPE@PETNPs) are obtained.
[0070] The SEM image of the fluorescent polyethylene terephthalate nanoparticles of the present invention is as follows: Figure 1 As shown, through Figure 1 It can be seen that the prepared polyethylene terephthalate nanoparticles are regular spherical and have relatively uniform size without aggregation; the FTIR image is as follows Figure 2 As shown, through Figure 2 It can be seen that for PET, 1724cm -1 The strong absorption peak at 1629cm is attributed to the stretching vibration of ester carbonyl (C=O); -1 and 1506cm -1 Corresponding to the (C=C) asymmetric and symmetric stretching vibrations of the benzene ring skeleton; 1250cm -1 The characteristic peak at is derived from the antisymmetric stretching vibration of the ester group (COC) coupled with the in-plane bending vibration of the benzene ring. Although the benzene ring vibration bands of PET and TPE (650-3500 cm -1 ) has peak overlap, but the TPE molecule has a peak at 625cm -1 and 576cm -1 The unique out-of-plane bending vibration doublet of vinyl (C=C) is present at the PET matrix, which serves as evidence of the successful loading of TPE into the PET matrix. FTIR spectral data clearly demonstrates the successful incorporation of TPE into PET NPs. Based on Example 1, the concentrations of tetraphenylethylene were adjusted to 0.05 mg / mL, 0.25 mg / mL, 0.50 mg / mL, and 0.75 mg / mL, respectively. The fluorescence spectra are shown in the figure below. Figure 3 As shown, through Figure 3 It can be seen that the fluorescence intensity of TPE@PETNPs increases significantly with the increase of TPE concentration.
[0071] Example 2
[0072] The polyethylene terephthalate (PET) used to produce the nanoparticles was obtained from soft drink bottles. The bottoms of the bottles were scored with a hacksaw blade to obtain fine debris, which was then screened to obtain particles with a size of 250-300 mesh. 0.5 g of the crushed PET particles was weighed and soaked in 100 mL of 1 mol / L sodium hydroxide solution for 60 minutes. After the alkaline wash, the particles were rinsed with copious amounts of deionized water until the rinse water was neutral, and then dried under vacuum at 80°C.
[0073] 0.025 g of polyethylene terephthalate was dissolved in 10 mL of hexafluoroisopropanol for 12 h at a dissolution temperature of 30 ° C and a rotation speed of 800 rpm. Use a syringe pump to add the polyethylene terephthalate solution to 100 mL of a 0.05 mg / mL sodium lauryl sulfate aqueous solution at room temperature at 2 mL / min. After the addition is completed at room temperature, stirring is continued for 2 h. In order to remove larger particles, the solution is filtered through a 0.45 μm nylon syringe filter. The solution is transferred to a 250 mL round-bottom flask and vacuum rotary evaporated to remove residual hexafluoroisopropanol. After reducing the volume in the round-bottom flask, 50 mL of ultrapure deionized water is added and subjected to a second rotary evaporation to obtain polyethylene terephthalate nanoparticles. The temperature of the rotary evaporator is 70 ° C and the vacuum degree is 0.04 MPa;
[0074] Take 0.1g of polyethylene terephthalate nanoparticles and add them to an aqueous solution containing 0.01g of Tween-20 and mix them. Use an ultrasonic cleaner with a power of 500W to treat the mixture for 40 minutes to ensure uniform dispersion. Dissolve 1mg of tetraphenylethylene in 2mL of tetrahydrofuran and add it to the nanoparticle dispersion at a rate of 5 drops / s. Maintain the temperature at 35°C and carry out the swelling reaction at a speed of 300rpm for 2 hours. After the swelling reaction is completed, remove the swelling agent and wash with ethanol-water solution. The washing process continues until the presence of tetraphenylethylene is no longer detected in the centrifuged supernatant using a UV spectrophotometer. Finally, fluorescently labeled nanoparticles are obtained.
[0075] Example 3
[0076] The polyethylene terephthalate (PET) used to produce the nanoparticles was obtained from soft drink bottles. The bottoms of the bottles were scored with a hacksaw blade to obtain fine debris, which was then screened to obtain particles with a size of 250-300 mesh. 1.5 g of the crushed PET particles were weighed and soaked in 100 mL of 1 mol / L sodium hydroxide solution for 60 minutes. After the alkaline wash, the particles were rinsed with copious amounts of deionized water until the rinse water was neutral, and then dried under vacuum at 80°C.
[0077] Dissolve 0.075 g of polyethylene terephthalate in 10 mL of trifluoroacetic acid for 24 h at a dissolution temperature of 50 ° C and a rotation speed of 500 rpm. Quickly pour the polyethylene terephthalate solution into 100 mL of deionized water while stirring continuously for 4 h. In order to remove larger particles, the solution was filtered through a 0.45 μm nylon syringe filter. The solution was transferred to a 250 mL round-bottom flask and vacuum rotary evaporated to remove residual trifluoroacetic acid. After reducing the volume in the round-bottom flask, 75 mL of ultrapure deionized water was added and rotary evaporated for a second time to obtain polyethylene terephthalate nanoparticles. The temperature of the rotary evaporator was 60 ° C and the vacuum degree was 0.04 MPa;
[0078] Take 0.05g of polyethylene terephthalate nanoparticles and add them to an aqueous solution containing 0.03g of Tween-20 and mix them. Use an ultrasonic cleaner with a power of 500W to treat the mixture for 20 minutes to ensure uniform dispersion. Dissolve 2mg of tetraphenylethylene in 2mL of tetrahydrofuran and add it to the nanoparticle dispersion. Maintain the temperature at 40°C and carry out the swelling reaction at a speed of 400rpm for 2 hours. After the swelling reaction is completed, remove the swelling agent and wash with ethanol-water solution. The washing process continues until the presence of tetraphenylethylene is no longer detected in the centrifuged supernatant using a UV spectrophotometer. Finally, fluorescently labeled nanoparticles are obtained.
[0079] Example 4
[0080] The polyethylene terephthalate (PET) used to produce the nanoparticles was obtained from soft drink bottles. The bottoms of the bottles were scored with a hacksaw blade to obtain fine debris, which was then screened to obtain particles with a size of 250-300 mesh. Two grams of the crushed PET particles were weighed and soaked in 500 mL of 1.5 mol / L sodium hydroxide solution for 45 minutes. After the alkaline wash, the particles were rinsed with copious amounts of deionized water until the rinse water was neutral, and then dried under vacuum at 60°C.
[0081] Dissolve 0.05g of polyethylene terephthalate in 10mL of hexafluoroisopropanol for 24h, with a dissolution temperature of 30℃ and a rotation speed of 800rpm. Use a syringe pump to add the polyethylene terephthalate solution to 100mL of deionized water at 3mL / min at room temperature. After the addition is completed at room temperature, stir continuously and continue stirring for 4h. In order to remove larger particles, filter the solution through a 0.45μm nylon syringe filter. Transfer the solution to a 250mL round-bottom flask and vacuum rotary evaporate to remove residual hexafluoroisopropanol. After reducing the volume in the round-bottom flask, add 100mL of ultrapure deionized water and rotary evaporate it a second time. The temperature of the rotary evaporator is 50℃ and the vacuum degree is 0.04Mpa;
[0082] Take 0.1g of polyethylene terephthalate nanoparticles and add 0.05g of Tween-20 to an aqueous solution and mix. Use an ultrasonic cleaner with a power of 500W to treat the mixture for 60 minutes to ensure uniform dispersion. Dissolve 2mg of tetraphenylethylene in 1mL of tetrahydrofuran and drip it into the nanoparticle dispersion at a rate of 5 drops / s. Keep the temperature at 50°C and carry out the swelling reaction at a speed of 600rpm for 4 hours. After the swelling reaction is completed, remove the swelling agent and wash with ethanol-water solution. The washing process continues until the presence of tetraphenylethylene is no longer detected in the centrifuged supernatant using a UV spectrophotometer. Finally, fluorescently labeled nanoparticles are obtained.
[0083] Example 5
[0084] The only difference between this embodiment and embodiment 1 is that the amount of polyethylene terephthalate nanoparticles is adjusted to 0.02 g, and the volumes of the sodium lauryl sulfate aqueous solution are set to 10 mL, 20 mL, 50 mL, 100 mL, and 150 mL, respectively.
[0085] The diameter and PDI value of the nanoparticles obtained above were tested, and the test results are shown in Table 1:
[0086] Table 1 Nanoparticle test results
[0087]
[0088] Table 1 shows that increasing the solvent volume ratio (V(H2O):V(HFIP), where V(H2O) refers to the volume of sodium dodecyl sulfate aqueous solution and V(HFIP) refers to the volume of hexafluoroisopropanol) from 1:1 to 15:1, reveals that the hydrodynamic diameter of PET NPs decreases from 537.2 nm to 98.3 nm, and the PDI decreases from 0.376 to 0.129. These results indicate that a higher solvent volume ratio significantly reduces the size of nanoplastics and optimizes their monodispersity. Undissolved polymer chains form large aggregates through an aggregation-ripening pathway. Significant large particle precipitates are observed at V(H2O):V(HFIP) ratios of 1:1, 2:1, and 5:1, leading to a failure of diffusion control. Systematic manipulation of the solvent volume ratio reveals its dual regulatory effect on both nanoplastic size and monodispersity. Adjusting the solvent volume ratio effectively modulates the nucleation and growth processes of nanoplastics, achieving precise control over their size and particle size distribution.
[0089] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0090] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing fluorescent polyethylene terephthalate nanoparticles, characterized in that: The steps include: 1) crushing and alkali-washing a raw material containing polyethylene terephthalate to obtain polyethylene terephthalate particles; 2) mixing the polyethylene terephthalate particles with an organic solvent to obtain a mixed solution, then mixing the mixed solution with a poor solvent for the polyethylene terephthalate particles, and filtering to obtain polyethylene terephthalate nanoparticles; 3) mixing polyethylene terephthalate nanoparticles with Tween-20 to obtain a nanoparticle dispersion; subjecting the nanoparticle dispersion to a swelling reaction with a tetraphenylethylene solution to obtain fluorescent polyethylene terephthalate nanoparticles.
2. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 1, wherein: The raw material containing polyethylene terephthalate includes polyethylene terephthalate plastic bottles.
3. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 2, wherein: The particle size after crushing in step 1) is 250-300 mesh; The alkaline solution for alkali washing includes one or more of sodium hydroxide solution, potassium hydroxide solution and ammonia water; the molar concentration of the alkaline solution is 0.1 to 5 mol / L; The alkali washing time is 30 to 60 minutes.
4. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to any one of claims 1 to 3, characterized in that: The volume ratio of the mixed solution in step 2) to the polyethylene terephthalate particle poor solvent is 1:10-15; The particle size of the polyethylene terephthalate nanoparticles obtained after the filtration is ≤0.45 μm.
5. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 4, wherein: The mass volume ratio of the polyethylene terephthalate particles to the organic solvent in the mixed solution in step 2) is 0.025-0.1 g:10 mL; The organic solvent in the mixed solution includes one or more of hexafluoroisopropanol, trifluoroacetic acid, chlorophenol, hydrofluoric acid, dimethylformamide, dimethyl sulfoxide and thionyl chloride; The poor solvent for polyethylene terephthalate particles includes water or an aqueous solution of sodium lauryl sulfate; The mass concentration of the sodium lauryl sulfate aqueous solution is 0.05 mg / mL.
6. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 5, wherein: The mixed solution in step 2) is mixed with the polyethylene terephthalate particle poor solvent by dropwise adding the mixed solution into the polyethylene terephthalate particle poor solvent; The dropping speed is 1-5 mL / min.
7. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 5 or 6, characterized in that: The mass volume ratio of the nanoparticle dispersion to the tetraphenylethylene solution in step 3) is 0.02-0.1 g: 1-2 mL; Before the swelling reaction, the tetraphenylethylene solution is added dropwise to the nanoparticle dispersion; The dropping speed is 2 to 5 drops / min.
8. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 7, wherein: The mass ratio of polyethylene terephthalate nanoparticles to Tween-20 in the nanoparticle dispersion in step 3) is 10:1-6; The mass volume ratio of tetraphenylethylene to solvent in the tetraphenylethylene solution is 1 mg: 1-2 mL; The solvent in the tetraphenylethylene solution includes one or more of tetrahydrofuran, acetone, dichloromethane and N,N-dimethylformamide.
9. The method for preparing fluorescent polyethylene terephthalate nanoparticles according to claim 8, wherein: The temperature of the swelling reaction in step 3) is 30-50° C., the swelling reaction time is 2-4 hours, and the stirring rate of the swelling reaction is 300-600 rpm.
10. Fluorescent polyethylene terephthalate nanoparticles prepared by the preparation method according to any one of claims 1 to 9.