Method for compatibilizing incompatible blends with metal organic framework nanoparticles having AIE properties

Abstract

The invention provides a preparation method of metal organic framework nano particles with AIE characteristics and a method for compatibilizing incompatible blends by using the metal organic framework nano particles with the AIE characteristics. According to the preparation method, polarity regulation and control of the MOF nanoparticles are realized by changing organic carboxylic acid ligands with different polarities, and the MOF nanoparticles with different polarities are prepared, so that distribution of the MOF nanoparticles in a blending system is controlled. The MOF nano particles are used as carriers to package aggregation-induced emission (AIE) molecules, so that the MOF nano particles are endowed with fluorescence characteristics, and the MOF nano particles with adjustable polarity and an AIE fluorescence response function are constructed. According to the invention, the MOF nanoparticles with AIE characteristics are used as a compatibilizer to compatibilize and modify an incompatible blend, so that the compatibility of the blend material is effectively improved, the mechanical property is improved, and in addition, the change conditions of the phase morphology and the distribution position of the MOF nanoparticles can be observed through a non-intrusive means.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to a method for preparing metal-organic framework nanoparticles with AIE characteristics, metal-organic framework nanoparticles with AIE characteristics, and a method for compatibilizing incompatible blends by using metal-organic framework nanoparticles with AIE characteristics. Background Art

[0002] Polymer materials have been widely used in various fields due to their excellent properties, easy processing, and functional diversity. A single polymer often has a shortcoming in a certain property. Therefore, polymer blends are usually prepared to obtain materials with good comprehensive properties. However, the entropy increase during polymer mixing is very limited, resulting in thermodynamic incompatibility, which leads to a decrease in the mechanical properties of the blend. Therefore, how to improve the compatibility between components in the blend is the key issue for obtaining blend materials with ideal mechanical properties.

[0003] Adding an appropriate amount of compatibilizer to improve the compatibility of the blend is a commonly used strategy in the industry. Traditional types of compatibilizers mainly include grafted and block copolymers, reactive compatibilizers, etc. Grafted and block copolymers improve compatibility by reducing the interfacial tension and enhancing the interfacial bonding; reactive compatibilizers contain active groups and can chemically react with the polymers in the blend to achieve strong interfacial bonding through chemical bonds, significantly improving the mechanical properties. However, for these types of compatibilizers, their compatibilization effects largely depend on the regulation of the chemical structure and relatively fine processing techniques. Therefore, these compatibilizers have certain limitations.

[0004] Nanoparticles have attracted extensive attention from researchers due to their flexible designability, multi-functional integration, and physical and chemical stability. Nanoparticles used as compatibilizers mainly include reactive nano-silica, graphene and its derivatives, and carbon quantum dots, etc. When nanoparticles are added to the blend system as compatibilizers, they rely on the adsorption at the interface to reduce the interfacial energy and refine the phase structure, thereby achieving the compatibilization effect. However, inappropriate nanoparticles or inappropriate amounts of nanoparticles added may cause the blend material to be brittle, and the dispersion degree of the nanoparticles will greatly affect the compatibilization effect. Therefore, the key lies in providing a controllable nanoparticle and regulating its dispersion in the blend system. Summary of the Invention

[0005] To solve the problems of poor compatibility during polymer blending and uncontrollable dispersion of nanoparticles as compatibilizers in the prior art, the present invention provides a metal-organic framework nanoparticle with AIE characteristics and a preparation method thereof, as well as a method for compatibilizing immiscible blends using the metal-organic framework nanoparticle with AIE characteristics. In the present invention, aggregation-induced emission molecules are encapsulated into metal-organic framework material (MOF) nanoparticles, and the polarity of the MOF nanoparticles is regulated by changing the type of organic ligand, so as to control the dispersion of the nanoparticles at the interface of the blend system, improve the interfacial adhesion, effectively improve the compatibility of the blend material and enhance the mechanical properties. In addition, the changes in the phase morphology and the distribution position of the MOF nanoparticles can be observed. This method has the advantages of simple preparation process, strong designability, excellent mechanical properties of the prepared compatibilized composite material, and non-invasive observation of the microstructure, etc.

[0006] The technical solution adopted in the present invention is as follows: A method for preparing a metal-organic framework nanoparticle with AIE characteristics, comprising the following steps:

[0007] S1. Dissolve a zirconium metal salt and an organic carboxylic acid ligand in a first solvent in a certain proportion, ultrasonically disperse and preheat to obtain a precursor solution containing MOF nanoparticles;

[0008] S2. Dissolve an aggregation-induced emission molecule and a regulator in a second solvent in a certain proportion, add them to the precursor solution, heat, and subject the reaction solution to post-treatment to obtain a metal-organic framework nanoparticle with AIE characteristics;

[0009] Wherein, the MOF nanoparticles have non-polar groups and / or polar groups;

[0010] The organic carboxylic acid ligand is selected from at least one of terephthalic acid (BDC), 2-methyl terephthalic acid (BDC-CH3), 2-trifluoromethyl terephthalic acid (BDC-CF3), 2-fluoroterephthalic acid (BDC-F), 2-aminoterephthalic acid (BDC-NH2).

[0011] Due to the rich variety of ligands of MOF and the convenience of functional modification, it provides conditions for the fine regulation of its polarity. In the present invention, the polarity of MOF nanoparticles is regulated by changing organic carboxylic acid ligands with different polarity sizes, and MOF nanoparticles with different polarities are prepared, thereby controlling the distribution of MOF nanoparticles in the blend system. Further, taking this MOF nanoparticle as a carrier, the aggregation-induced emission (AIE) molecule tetracarboxytetraphenylethylene (TCPE) is encapsulated, thereby endowing it with fluorescence characteristics, and a kind of MOF nanoparticle with both adjustable polarity and AIE fluorescence response function is constructed. The present invention also uses this MOF nanoparticle with AIE characteristics as a compatibilizer to compatibilize and modify incompatible blends. Specifically, it is mixed with polypropylene and polystyrene in a certain proportion by melt blending method to prepare a composite material. The experimental results show that this MOF nanoparticle with AIE characteristics can effectively improve the compatibility of the blend, significantly reduce the interfacial gap in the blend system, enhance the toughness while improving the strength of the composite material. At the same time, since the TCPE molecule is restricted in the MOF pore channels, the intramolecular rotation is hindered to trigger the AIE effect, endowing the MOF nanoparticle with fluorescence characteristics, which can in-situ monitor the phase morphology evolution and filler dispersion of the blend during the deformation process, and has the advantage of non-invasive monitoring.

[0012] Specifically, in step S1 of the present invention, the polarity of MOF nanoparticles is regulated by changing organic carboxylic acid ligands with different polarity sizes. When preparing MOF nanoparticles with non-polar groups, 2-methyl terephthalic acid or 2-trifluoromethyl terephthalic acid can be selected as the organic carboxylic acid ligand. When preparing MOF nanoparticles with polar groups, 2-aminoterephthalic acid or 2-fluoroterephthalic acid can be selected as the organic carboxylic acid ligand. When preparing MOF nanoparticles with both polar groups and non-polar groups, 2-aminoterephthalic acid and 2-trifluoromethyl terephthalic acid can be selected as the organic carboxylic acid ligands at the same time.

[0013] Preferably, the organic carboxylic acid ligand is selected from 2-trifluoromethyl terephthalic acid and 2-aminoterephthalic acid.

[0014] Preferably, the molar ratio of 2-trifluoromethyl terephthalic acid to 2-aminoterephthalic acid is 1:1 to 1.2, preferably 1:1.

[0015] Preferably, the molar ratio of the zirconium metal salt to the organic carboxylic acid ligand is 1:1 to 1.5, preferably 1:1.

[0016] Preferably, the zirconium metal salt is zirconium chloride.

[0017] Preferably, the first solvent is N,N-dimethylformamide, and the mass ratio of the first solvent to the first raw material is 35:950 - 1400, preferably 35:950; the first raw material includes a zirconium metal salt and an organic carboxylic acid ligand.

[0018] Preferably, the time of ultrasonic treatment is 3 - 5 min, preferably 3 min. The purpose of ultrasonic treatment is to uniformly disperse the metal salt and the organic carboxylic acid ligand in the solution.

[0019] Preferably, in step S1, the preheating temperature is 80 - 85 °C, and the preheating time is 1 - 1.5 h.

[0020] Preferably, the aggregation-induced emission molecule is tetracarboxytetraphenylethylene; and / or the regulator is benzoic acid.

[0021] Preferably, the mass ratio of tetracarboxytetraphenylethylene to benzoic acid is 1:35 - 83, preferably 1:35.

[0022] Preferably, the second solvent is N,N-dimethylformamide, and the mass ratio of the solvent to the second raw material is 25:47 - 60, preferably 25:47; the second raw material includes an aggregation-induced emission molecule and a regulator.

[0023] Preferably, in step S2, the heating temperature is 120 - 150 °C, and the heating time is 24 - 36 h.

[0024] Preferably, the post-treatment method includes: centrifuging the reaction solution, washing the obtained precipitate with ethanol by centrifugation 3 - 4 times, and drying it at 60 - 65 °C for 24 - 36 h (preferably drying at 60 °C for 24 h) to obtain metal-organic framework nanoparticles with AIE properties.

[0025] The present invention also provides the metal-organic framework nanoparticles with AIE properties prepared by the method described above.

[0026] The present invention also provides a method for compatibilizing immiscible blends with metal-organic framework nanoparticles with AIE properties, including: melt-blending metal-organic framework nanoparticles with AIE properties, polypropylene, and polystyrene in a certain proportion to obtain a composite material, and obtaining a composite material sheet by compression molding.

[0027] Preferably, the mass ratio of polypropylene, polystyrene, and metal-organic framework nanoparticles with AIE properties is 70:30:0.1 - 1.

[0028] Preferably, the melt-blending is carried out using an extruder, the blending temperature is 200 - 210 °C, and the screw speed is 60 - 70 rpm.

[0029] Preferably, the temperature for compression molding is 190-200°C, the pre-pressing pressure is 4 MPa, the pre-pressing time is 1 min, the holding pressure is 10 Mpa, and the holding time is 2 min.

[0030] Advantages of the present invention: In the present invention, zirconium salt is used as the metal source, and MOF nanoparticles with different polarities are prepared by adjusting the types of functional groups of the organic ligands. The MOF nanoparticles are used as carriers to load aggregation-induced emission molecules, and MOF nanoparticles with both compatibilizing function and fluorescence tracing ability are obtained. The prepared MOF nanoparticles with AIE characteristics are added as compatibilizers to the blend system of the copolymer, and the compatibility of the prepared blend material is improved, and the mechanical properties are significantly enhanced. The present invention proposes a simple process for compatibilizing and modifying incompatible blends. By introducing MOF nanoparticles as compatibilizers and regulating their distribution positions in the blend system by changing their polarity sizes, the phase diameter of the dispersed phase is finally reduced, and the interfacial gap is reduced, achieving the effect of enhancing and toughening. In addition, due to the integration of AIE fluorescence tracing function in MOF nanoparticles, the distribution and phase structure of nanoparticles can be dynamically monitored without damaging the material. Description of the Drawings

[0031] Figure 1 It is the stress-strain curve diagram of the sheet samples prepared in Examples 1-6 and Comparative Example 1 of the present invention.

[0032] Figure 2 It is the scanning electron microscope image of the cross-sectional morphology of the sheet samples prepared in Examples 1-6 and Comparative Example 1 of the present invention.

[0033] Figure 3 It is the scanning electron microscope image of the phase structure change during the tensile process of the sheet sample prepared in Example 1 of the present invention.

[0034] Figure 4 It is the laser confocal image of the dispersion position of MOF in the system during the tensile process of the sheet sample prepared in Example 1 of the present invention.

[0035] Figure 5 It is the scanning electron microscope image of the phase structure change during the tensile process of the sheet sample prepared in Comparative Example 1 of the present invention. Detailed Embodiments

[0036] The following describes the implementation modes of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. In the embodiments of the present invention, the methods used are all conventional methods unless otherwise specified, and the reagents used can all be obtained from commercial channels.

[0037] Example 1

[0038] First, prepare MOF nanoparticles with a ligand of BDC-NH2∶BDC-CF3 = 1∶1. Weigh 0.1500 g (0.640 mmol) of ZrCl4, 0.0590 g (0.320 mmol) of BDC-NH2, and 0.0750 g (0.320 mmol) of BDC-CF3. Dissolve the above three chemicals together in 10 ml of N,N-dimethylformamide. After complete dissolution, a precursor solution is obtained. Place the precursor solution in an oil bath device and heat it at 85°C for 1 h. Then weigh 0.030 g (0.059 mmol) of tetracarboxytetraphenylethylene and 2.5 g (0.020 mol) of benzoic acid. Dissolve the two chemicals together in 5 ml of N,N-dimethylformamide to prepare a solution. Add the prepared solution to the precursor solution and continue heating at 150°C for 24 h. Centrifuge the solution obtained after the heating reaction at a rate of 8000 rpm for 3 min, and then pour off a part of the supernatant after centrifugation. Then wash the precipitate with 10 ml of ethanol, centrifuge at a rate of 8000 rpm for 3 min, and pour off the upper-layer ethanol. Repeat the above steps three times. Finally, dry the obtained precipitate part in a vacuum oven at 60°C for 12 h to prepare MOF nanoparticles with a ligand of BDC-NH2∶BDC-CF3 = 1∶1. Blend 14.0 g of polypropylene (E02ES, produced by Sinopec Zhenhai Refining & Chemical Company), 6.0 g of polystyrene (PG33, produced by Chi Mei Chemical Co., Ltd.), and 0.2 g of nanoparticle filler with a ligand of BDC-NH2∶BDC-CF3 = 1∶1. Add the mixture to a micro-extruder for blending. The blending temperature is 200°C and the rotation speed is 60 rpm. Then, use a tablet press to mold the sample into a sheet at a temperature of 190°C, and use a sample preparation machine to cut the sheet to obtain tensile specimens. Measure its mechanical properties with an electronic universal testing machine, observe the morphology of the cross-section through a scanning electron microscope. In addition, observe the phase morphology structure at different stages during the tensile process of the specimen using a laser confocal microscope, and simultaneously observe the phase morphology structure at the corresponding stages during the tensile process of the sample through a cold field emission scanning electron microscope. The relevant parameters of the mechanical properties are shown in Table 1, and the stress-strain curve is asFigure 1 As shown, the scanning electron microscope image of the sample cross-section morphology is as Figure 2 shown, and the scanning electron microscope image and laser confocal image of the phase structure change of the sample during the stretching process are respectively as Figure 3 and Figure 4 shown.

[0039] Example 2

[0040] First, prepare MOF nanoparticles with BDC-CH3 as the ligand. Weigh 0.1500 g (0.640 mmol) of ZrCl4 and 0.1153 g (0.640 mmol) of BDC-CH3. Dissolve the above two chemicals together in 10 ml of N,N-dimethylformamide. After complete dissolution, a precursor solution is obtained. Place the precursor solution in an oil bath device and heat it at 85 °C for 1 h. Then weigh 0.030 g (0.059 mmol) of tetracarboxytetraphenylethylene and 2.5 g (0.020 mol) of benzoic acid. Dissolve the two chemicals together in 5 ml of N,N-dimethylformamide to prepare a solution. Add the prepared solution to the precursor solution and continue to heat at 150 °C for 24 h. Centrifuge the solution obtained after the heating reaction at a rate of 8000 rpm for 3 min, and then pour off a part of the supernatant after centrifugation. Then wash the precipitate with 10 ml of ethanol, centrifuge at a rate of 8000 rpm for 3 min, and pour off the upper layer of ethanol. Repeat the above steps three times. Finally, dry the obtained precipitate in a vacuum oven at 60 °C for 12 h to prepare MOF nanoparticles with BDC-CH3 as the ligand. Blend 14.0 g of polypropylene (E02ES, produced by Zhenhai Refining & Chemical Company, Sinopec), 6.0 g of polystyrene (PG33, produced by Chi Mei Chemical Co., Ltd.), and 0.2 g of the nanoparticle filler with BDC-CH3 as the ligand. Add the mixture to a micro-extruder for blending. The blending temperature is 200 °C and the rotation speed is 60 rpm. Then, use a tablet press to mold the mixture into a sheet sample at a temperature of 190 °C, and use a sample preparation machine to cut the sheet to obtain tensile specimens. Use an electronic universal testing machine to measure its mechanical properties, and observe the morphology of the cross-section through a scanning electron microscope. The relevant parameters of the mechanical properties are shown in Table 1, and the stress-strain curve is as Figure 1 shown, and the scanning electron microscope image of the sample cross-section morphology is as Figure 2 shown

[0041] Example 3

[0042] First, prepare MOF nanoparticles with BDC-CF3 as the ligand. Weigh 0.1500 g (0.640 mmol) of ZrCl4 and 0.1498 g (0.640 mmol) of BDC-CH3. Dissolve the above two chemicals together in 10 ml of N,N-dimethylformamide. After complete dissolution, a precursor solution is obtained. Place the precursor solution in an oil bath device and heat it at 85 °C for 1 h. Then weigh 0.030 g (0.059 mmol) of tetracarboxytetraphenylethylene and 2.5 g (0.020 mol) of benzoic acid. Dissolve the two chemicals together in 5 ml of N,N-dimethylformamide to prepare a solution. Add the prepared solution to the precursor solution and continue to heat at 150 °C for 24 h. Centrifuge the solution obtained after the heating reaction at a rate of 8000 rpm for 3 min, and then pour off a part of the supernatant after centrifugation. Then wash the precipitate with 10 ml of ethanol, centrifuge at a rate of 8000 rpm for 3 min, and pour off the upper layer of ethanol. Repeat the above steps three times. Finally, dry the obtained precipitate part in a vacuum oven at 60 °C for 12 h to prepare MOF nanoparticles with BDC-CF3 as the ligand. Blend 14.0 g of polypropylene (E02ES, produced by Sinopec Zhenhai Refining & Chemical Company), 6.0 g of polystyrene (PG33, produced by Chi Mei Chemical Co., Ltd.), and 0.2 g of the nanofiller of MOF nanoparticles with BDC-CF3 as the ligand. Add the mixture to a micro-extruder for blending. The blending temperature is 200 °C and the rotation speed is 60 rpm. Then, use a tablet press to mold the sample into a sheet at a temperature of 190 °C, and use a sample preparation machine to cut the sheet to obtain tensile test specimens. Use an electronic universal testing machine to measure its mechanical properties, and observe the morphology of the cross-section through a scanning electron microscope. The relevant parameters of the mechanical properties are shown in Table 1, and the stress-strain curve is as Figure 1 shown, and the scanning electron microscope image of the cross-section morphology of the sample is as Figure 2 shown

[0043] Example 4

[0044] First, prepare MOF nanoparticles with BDC-F as the ligand. Weigh 0.1500 g (0.640 mmol) of ZrCl4 and 0.1178 g (0.640 mmol) of BDC-F. Dissolve the above two chemicals together in 10 ml of N,N-dimethylformamide. After complete dissolution, a precursor solution is obtained. Place the precursor solution in an oil bath device and heat it at 85 °C for 1 h. Then weigh 0.030 g (0.059 mmol) of tetracarboxytetraphenylethylene and 2.5 g (0.020 mol) of benzoic acid. Dissolve the two chemicals together in 5 ml of N,N-dimethylformamide to prepare a solution. Add the prepared solution to the precursor solution and continue heating at 150 °C for 24 h. Centrifuge the solution obtained after the heating reaction at a rate of 8000 rpm for 3 min, and then pour off a part of the supernatant after centrifugation. Then wash the precipitate with 10 ml of ethanol, centrifuge at a rate of 8000 rpm for 3 min, and pour off the upper layer of ethanol. Repeat the above steps three times. Finally, dry the obtained precipitate in a vacuum oven at 60 °C for 12 h to prepare MOF nanoparticles with BDC-F as the ligand. Blend 14.0 g of polypropylene (E02ES, produced by Sinopec Zhenhai Refining & Chemical Company), 6.0 g of polystyrene (PG33, produced by Chi Mei Chemical Co., Ltd.), and 0.2 g of the nanofiller of MOF nanoparticles with BDC-F as the ligand. Add the mixture to a micro-extruder for blending. The blending temperature is 200 °C and the rotation speed is 60 rpm. Then, use a tablet press to mold the sample into a sheet at a temperature of 190 °C, and use a sample cutter to cut the sheet to obtain tensile splines. Measure its mechanical properties with an electronic universal testing machine, and observe the morphology of the cross-section through a scanning electron microscope. The relevant parameters of the mechanical properties are shown in Table 1, and the stress-strain curve is as Figure 1 shown, and the scanning electron microscope image of the cross-section morphology of the sample is as Figure 2 shown

[0045] Example 5

[0046] First, prepare MOF nanoparticles with BDC-NH2 as the ligand. Weigh 0.1500 g (0.640 mmol) of ZrCl4 and 0.1159 g (0.640 mmol) of BDC-NH2. Dissolve the above two chemicals together in 10 ml of N,N-dimethylformamide. After complete dissolution, a precursor solution is obtained. Place the precursor solution in an oil bath device and heat it at 85 °C for 1 h. Then weigh 0.030 g (0.059 mmol) of tetracarboxytetraphenylethylene and 2.5 g (0.020 mol) of benzoic acid. Dissolve the two chemicals together in 5 ml of N,N-dimethylformamide to prepare a solution. Add the prepared solution to the precursor solution and continue to heat at 150 °C for 24 h. After the heating reaction is completed, centrifuge the resulting solution at a rate of 8000 rpm for 3 min, and then pour out a part of the supernatant after centrifugation. Then wash the precipitate with 10 ml of ethanol, centrifuge at a rate of 8000 rpm for 3 min, and pour out the upper layer of ethanol. Repeat the above steps three times. Finally, dry the obtained precipitate part in a vacuum oven at 60 °C for 12 h to prepare MOF nanoparticles with BDC-NH2 as the ligand. Blend 14.0 g of polypropylene (E02ES, produced by Zhenhai Refining & Chemical Company, Sinopec), 6.0 g of polystyrene (PG33, produced by Chi Mei Chemical Co., Ltd.), and 0.2 g of the nanofiller of MOF nanoparticles with BDC-NH2. Add the mixture to a micro-extruder for blending. The blending temperature is 200 °C and the rotation speed is 60 rpm. Then, use a tablet press to mold the mixture into a sheet sample at a temperature of 190 °C, and use a sample preparation machine to cut the sheet to obtain tensile test specimens. Use an electronic universal testing machine to measure its mechanical properties, and observe the morphology of the cross-section through a scanning electron microscope. The relevant parameters of the mechanical properties are shown in Table 1, and the stress-strain curve is as Figure 1 shown, and the scanning electron microscope image of the cross-section morphology of the sample is as Figure 2 shown

[0047] Comparative Example 1

[0048] Blend 14.0 g of polypropylene (E02ES, produced by Zhenhai Refining & Chemical Company, Sinopec) and 6.0 g of polystyrene (PG33, produced by Chi Mei Chemical Co., Ltd.). Add the mixture to a micro-extruder for blending. The blending temperature is 200 °C and the rotation speed is 60 rpm. Then, use a tablet press to mold the mixture into a sheet sample at a temperature of 190 °C, and use a sample preparation machine to cut the sheet to obtain tensile test specimens. Use an electronic universal testing machine to measure its mechanical properties, and at the same time, observe the morphology of the cross-section of the sample and the phase morphology structure at the corresponding stage during the stretching process through a cold field emission scanning electron microscope. The relevant parameters of the mechanical properties are shown in Table 1, and the stress-strain curve is as Figure 1 shown, and the scanning electron microscope images of the cross-section morphology of the sample and the phase structure change during the stretching process are respectively as Figure 2 , Figure 5 shown

[0049] Table 1. Parameters related to mechanical properties

[0050]

[0051] From Figure 1 and Table 1, it can be seen that when the content of nanoparticle fillers is 1 wt%, the polarity of the functional groups on the organic ligand will affect its compatibilization effect. When the organic ligands of MOF nanoparticles are BDC-NH2 and BDC-CF3, and the ratio of the two is 1:1, the compatibilization effect is the best. Compared with the component without the compatibilizing filler, the elongation at break is increased by 846%, the tensile toughness is increased by 892%, the Young's modulus is increased by 4.6%, and the tensile strength is increased by 8.9%.

[0052] From Figure 2 the comparison of the cross-sectional morphology diagrams of different samples, it can be seen that after adding MOF nanoparticles to the polypropylene / polystyrene blend system, the phase domains of the polystyrene dispersed phase become smaller. In the blend system with MOF nanoparticles having both polar and non-polar groups, not only the dispersed phase domains are reduced, but also the two-phase interface becomes blurred, and the gap at the interface is significantly reduced, improving the compatibility of the blend system. This is because by adjusting the polarity of the MOF nanoparticles, the dispersion of the MOF nanoparticles at the interface of the blend system is controlled. When the MOF nanoparticles are dispersed at the two-phase interface, a steric hindrance effect can be formed to prevent the aggregation of the dispersed phase, reduce the size of the dispersed phase domains, and stabilize the microstructure of the blend. On the other hand, the polar groups (amino groups) on the MOF nanoparticles form π-π stacking interactions with the π electron clouds of the benzene rings in polystyrene, while the non-polar groups (trifluoromethyl groups) on the MOF nanoparticles can bind to the non-polar alkane chain segments of polypropylene through van der Waals forces, reducing the interfacial energy of the MOF nanoparticles on the surface of polypropylene. This makes the MOF nanoparticles act as a "bridge", reducing the interfacial tension between the two phases and inhibiting phase separation. From Figure 3 and Figure 5 it can be seen that when stressed, in the sample without MOF nanoparticles, after the polystyrene phase undergoes a certain degree of deformation, the polystyrene phase is pulled out from the matrix, and finally the sample fractures. However, after adding MOF nanoparticles, when the material is stressed, the degree of deformation of the polystyrene phase increases greatly, and until finally the polypropylene matrix also deforms, the polystyrene phase detaches from the matrix. This shows that the bonding between the two phases has been significantly improved, and stress can be effectively transferred between the two phases, ultimately leading to the improvement of the mechanical properties of the blend material. From Figure 4It can be seen that we directly observed the phase structure changes and the distribution positions of MOF nanoparticles at different stages during the stretching process of the sample through a laser confocal microscope. Since the MOF nanoparticles are dispersed at the two-phase interface, the process of the dispersed phase gradually stretching and deforming until falling off can be observed more clearly. The MOF nanoparticles are also initially dispersed at the interface and then randomly dispersed in the blend system along with the falling off of the dispersed phase. Comparing Figure 3 with the scanning electron micrographs in

[0053] , it can be found that this dynamic non-invasive observation method can more accurately reflect the microscopic structure changes during the force application process of the sample. Generally speaking, the polypropylene / polystyrene composite material prepared by this method has good mechanical properties and endows the material with the characteristics of dynamically monitoring the filler distribution and phase structure, showing obvious advantages and characteristics compared with the compatibility of the blend modified with traditional compatibilizers. The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing metal-organic framework nanoparticles with AIE properties, characterized in that, It includes the following steps: S1. Dissolve a zirconium metal salt and an organic carboxylic acid ligand in a first solvent in a certain proportion, preheat after ultrasonic dispersion to obtain a precursor solution containing MOF nanoparticles; S2. Dissolve an aggregation-induced emission molecule and a regulator in a second solvent in a certain proportion, add them to the precursor solution, heat, and subject the reaction solution to post-treatment to obtain metal-organic framework nanoparticles with AIE characteristics; Among them, the MOF nanoparticles have non-polar groups and / or polar groups; The organic carboxylic acid ligand is selected from at least one of terephthalic acid, 2-methyl terephthalic acid, 2-trifluoromethyl terephthalic acid, 2-fluoroterephthalic acid, and 2-aminoterephthalic acid.

2. The method according to claim 1, characterized in that, The organic carboxylic acid ligand is selected from 2-trifluoromethyl terephthalic acid and 2-aminoterephthalic acid.

3. The method according to claim 2, wherein The molar ratio of 2-trifluoromethyl terephthalic acid to 2-aminoterephthalic acid is 1:1 to 1.

2.

4. The method according to claim 1, characterized in that, In step S1, the preheating temperature is 80-85°C, and the preheating time is 1-1.5 h.

5. The method according to claim 1, characterized in that The aggregation-induced emission molecule is tetracarboxytetraphenylethylene; and / or the regulator is benzoic acid.

6. The method according to claim 1, wherein In step S2, the heating temperature is 120-150°C, and the heating time is 24-36 h.

7. Metal-organic framework nanoparticles with AIE characteristics prepared by the method according to any one of claims 1-6.

8. Method for compatibilizing incompatible blends with hybrid ligand metal-organic framework nanoparticles having AIE properties, characterized in that, It includes: Melt-blend the metal-organic framework nanoparticles with AIE characteristics prepared by the method according to any one of claims 1-6 or the metal-organic framework nanoparticles with AIE characteristics according to claim 7, polypropylene, and polystyrene in a certain proportion to obtain a composite material, and obtain a composite material plate by compression molding.

9. The method according to claim 8, wherein, The mass ratio of polypropylene, polystyrene, and metal-organic framework nanoparticles with AIE characteristics is 70:30:0.1-1.

10. The method according to claim 8, characterized in that Perform the above-mentioned melt-blending using an extruder, the blending temperature is 200-210°C, and the screw speed is 60-70 rpm.

Images