A zeolite imidazolate framework open nanostructured functional flame retardant and its preparation method and application

Abstract

The present invention relates to a zeolite imidazolate framework open nanostructured functional flame retardant and a preparation method and application thereof, belonging to the technical field of advanced functional materials. The present invention provides a zeolite imidazolate framework open nanostructured functional flame retardant having a unique yolk-shell structure, the surface of which has a large number of mesopores and macropore structures added on the basis of the micropore structure of the zeolite imidazolate framework. The presence of a multi-level pore structure is beneficial to the adsorption of flammable gases and toxic and harmful gases during the combustion of polymer materials, and enhances the smoke suppression effect of the flame retardant. There is a good synergistic effect between the ferrocene grafted on the zeolite imidazolate framework and the zeolite imidazolate framework, which can enhance the flame retardant efficiency of the functional flame retardant and at the same time give it excellent ultraviolet absorption ability. In addition, the introduction of ferrocene can effectively improve the compatibility between the functional flame retardant and the polymer matrix, thereby enhancing the mechanical properties of the polymer.

Description

Technical Field

[0001] The invention relates to a zeolite imidazolate framework open nanostructured functional flame retardant and a preparation method and application thereof, belonging to the technical field of advanced functional materials. Background Art

[0002] Due to their outstanding properties, polymers are widely used in daily life and industrial production. Despite their ubiquity, their flammability severely limits their further application. They can also lead to the intensification of fires and the release of toxic gases, resulting in significant damage to property and life. Therefore, research on the fire safety of polymer materials is crucial and urgent.

[0003] At present, the flame retardant properties of polymer materials are generally improved by adding flame retardants. Halogen flame retardants are a type of flame retardant that has a significant effect on improving the flame retardant properties of materials and still occupy a very large share in the market. However, the presence of halogens will release toxic and harmful substances while exerting their effects, causing serious harm to the human body and the environment. Therefore, the share of halogen flame retardants is decreasing year by year. Both domestic and foreign countries are pursuing the addition of green and environmentally friendly flame retardants while ensuring the flame retardant effect. Metal-Organic Frameworks (MOFs)-based flame retardants are an outstanding example.

[0004] Research on MOF-based flame retardants has flourished in recent years, particularly in the field of polymer flame retardancy. Zeolitic imidazolate frameworks (ZIFs) have attracted considerable attention due to their simple synthesis, low raw material costs, and environmental friendliness. Their ease of modification allows for a wide range of post-treatment methods, enabling them to be formulated with other flame retardants to achieve even higher flame retardancy. ZIFs inherently possess superior porosity, a large surface area, and a rich microporous structure, enabling them to adsorb small molecules of combustible and harmful gases, providing excellent smoke suppression. However, ZIFs are unable to effectively suppress the release of large flammable and harmful components during polymer combustion. Therefore, the development of ZIFs as highly effective functional flame retardants with open nanostructures by combining them with other compounds and etching them to create a hierarchical pore system has become a challenging and significant research direction. Summary of the Invention

[0005] The technical problem solved by the present invention is to overcome the shortcomings of the existing technology, that is, the current MOFs-based flame retardants, like ZIFs-based flame retardants, are generally microporous materials, which are difficult to adsorb large molecular combustible gases and harmful gases released during the combustion of polymer substrates. A zeolite imidazolate framework open nanostructured functional flame retardant and its preparation method and application are proposed, and an open nanostructured functional flame retardant with a yolk-shell structure and a multi-level pore structure is obtained through a synchronous etching and surface growth strategy.

[0006] The technical solution of the present invention is:

[0007] A zeolite imidazolate framework open nanostructured functional flame retardant, comprising a zeolite imidazolate framework grafted with a ferrocene polymer network, the zeolite imidazolate framework grafted with the ferrocene polymer network having micropores, mesopores, and macropores, with the micropore size being 1.5-2.5 nm, the mesopore size being 30-50 nm, and the macropore size being 70-120 nm;

[0008] A method for preparing a zeolite imidazolate framework grafted with a ferrocene polymeric network, the method comprising the steps of:

[0009] In the first step, the aminated zeolite imidazolate framework is dispersed in methanol to obtain a dispersion;

[0010] The ratio of the aminated zeolite imidazolate framework to methanol is 0.5 g: 50-100 ml;

[0011] In the second step, a methanol solution of ferrocenecarboxaldehyde is added to the dispersion obtained in the first step, and the mixture is heated to react at a temperature of 55-65°C for 12-24 hours. After the reaction is completed, the mixture is cooled to room temperature and centrifuged. The filter cake is washed three times with ethanol and then dried in an oven at 50-60°C for 12-24 hours to obtain a solid.

[0012] In the ferrocene formaldehyde solution, the ratio of ferrocene formaldehyde to methanol is 0.5g:50-100ml;

[0013] The ratio of ferrocene carboxaldehyde to the aminated zeolite imidazolate framework is 1g:0.5-1.5g;

[0014] In the third step, the solid obtained in the second step is dispersed in 1,2-dichloroethane, and then a 1,2-dichloroethane solution of ferrocene and a catalyst dimethylformal and boron trifluoride ether are added, and the mixture is reacted at 70-80°C for 4-5 hours. After the reaction is completed, the mixture is cooled to room temperature and centrifuged. The filter cake is washed three times with ethanol and then dried in an oven at 50-60°C for 12-24 hours to obtain a zeolite imidazole ester framework open nanostructured flame retardant.

[0015] The ratio of the solid to 1,2-dichloroethane is 0.5 g: 100-150 ml;

[0016] In the 1,2-dichloroethane solution of ferrocene, the ratio of ferrocene to 1,2-dichloroethane is 1g:100-150ml;

[0017] The ratio of the solid, ferrocene, dimethanol formal and boron trifluoride etherate is 0.5g: 0.5-1.5g: 5-7g: 2-3g.

[0018] Application of a zeolite imidazolate framework open nanostructured functional flame retardant in epoxy resin, comprising the following steps:

[0019] The ethanol dispersion of the zeolite imidazolate framework open nanostructured functional flame retardant, epoxy resin and curing agent are stirred and mixed, and then heated to cure to obtain an epoxy resin composite material;

[0020] In the ethanol dispersion of the zeolite imidazolate framework open nanostructured functional flame retardant, the ratio of the zeolite imidazolate framework open nanostructured flame retardant to ethanol is 5g:5-15ml;

[0021] The curing agent is 4,4-diphenyl diphenyl sulfone (DDS);

[0022] The ratio of the zeolite imidazolate framework open nanostructure functional flame retardant, epoxy resin and curing agent is 5g:50-100g:25-35g;

[0023] The model of the epoxy resin is E-44 epoxy resin;

[0024] The curing temperature is 170-180℃ and the curing time is 3-4h.

[0025] Beneficial effects

[0026] The zeolite imidazolate framework functional flame retardant provided by the present invention is the first flame retardant with an open nanostructure. The zeolite imidazolate framework open nanostructure functional flame retardant provided by the present invention presents a unique egg yolk-shell structure. The zeolite imidazolate framework open nanostructure flame retardant provided by the present invention has large channels with open pores on the surface, and adds many mesoporous and macroporous structures on the basis of the rich micropores of ZIF-67. The existence of the multi-level pore structure is beneficial to the adsorption of flammable gases and toxic and harmful gases during the combustion of polymer materials, and enhances the smoke suppression effect of the flame retardant. There is a good synergistic effect between the ferrocene grafted on the zeolite imidazolate framework and the zeolite imidazolate framework, which can enhance the flame retardant efficiency of the functional flame retardant and give it excellent ultraviolet absorption ability. In addition, the introduction of ferrocene can effectively improve the compatibility between the functional flame retardant and the polymer matrix, thereby enhancing the mechanical properties of the polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a transmission electron micrograph of the functional flame retardant prepared in Example 1;

[0028] Figure 2 The nitrogen adsorption-desorption isotherm curve and pore size distribution curve of the functional flame retardant prepared in Example 1;

[0029] Figure 3 This is the ultraviolet absorption curve of the functional flame retardant prepared in Example 1. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the following embodiments:

[0031] Example

[0032] A method for preparing a partially etched zeolite imidazolate framework open nanostructured functional flame retardant comprises the following steps:

[0033] S1. Preparation of ZIF-67:

[0034] 2.91 g of cobalt nitrate hexahydrate and 3.28 g of 2-methylimidazole were dissolved in 100 ml of methanol, mixed, and stirred for 1 hour. The mixture was then allowed to stand for 24 hours. The solid was separated by centrifugation, washed three times with methanol, and dried in an oven at 60°C for 24 hours to obtain ZIF-67.

[0035] S2, amino-ZIF-67:

[0036] 0.5 g of ZIF-67 was dispersed in 50 ml of methanol by waterbath sonication for 10 minutes. Subsequently, 0.5 g of 3,5-diamino-1,2,4-triazole was dissolved in 50 ml of methanol. The mixture was stirred and reacted for 12 hours. The solid was separated by centrifugation, washed three times with methanol, and dried in a 60°C oven for 24 hours to obtain amino-ZIF-67 (NH2-ZIF).

[0037] S3. Amination of ZIF-67 loaded with iron-containing compounds:

[0038] 0.5g of NH2-ZIF was dispersed in 50ml of methanol by waterbath sonication for 10 minutes. Then, 50ml of a methanol solution containing 0.5g of ferrocenecarboxaldehyde was added and stirred at room temperature for 1 hour. The mixed solution was then refluxed at 60°C for 24 hours and cooled to room temperature. The solid was separated by centrifugation, washed three times with methanol, and dried in a 60°C oven for 24 hours to obtain an amino-ZIF-67-loaded iron compound composite flame retardant (Fc-ZIF).

[0039] S4, zeolite imidazolate framework open nanostructure functional flame retardant:

[0040] 0.5g of Fe-Co-MOF / ZIF was dispersed in 100ml of 1,2-dichloroethane by waterbath sonication for 10 minutes. 100ml of a dichloroethane solution containing 1g of ferrocene was then added and stirred at room temperature for 30 minutes. 6g of dimethylformal was then added and stirred at 60°C for 30 minutes. 2.4g of boron trifluoride etherate was then added and the mixture was reacted at 80°C for 24 hours. The solid was separated by filtration, washed multiple times with ethanol, and dried in a 60°C oven for 24 hours to obtain a partially etched zeolite imidazolate framework open nanostructured functional flame retardant (Fc-CMOPP@Fc-Fc-ZIF).

[0041] Figure 1 This is a transmission electron micrograph of the functional flame retardant prepared in the example, showing its interesting yolk-shell structure. Figure 2 : is the pore size distribution curve of the functional flame retardant prepared in the example, and its rich multi-level pore structure can be seen. Figure 3 The UV absorption curve of the functional flame retardant prepared in the example shows its excellent UV absorption performance.

[0042] Application of the prepared flame retardant in epoxy resin:

[0043] 100 g of E-44 epoxy resin was weighed into a flask, and 10 ml of an ethanol solution containing 5 g of Fc / Fe-Co-MOF / ZIF was added. The mixture was stirred at 140°C for 10 minutes, followed by the addition of 30 g of 4,4-diphenyldiphenyl sulfone (DDS) and stirring for 10 minutes. The mixture was vacuumed for 30 minutes and then transferred to a preheated polytetrafluoroethylene mold and cured at 180°C for 4 hours.

[0044] The flame retardant properties of the prepared epoxy resin composite material were tested (the limiting oxygen index was obtained according to ASTMD 2863; the UL-94 grade was obtained according to UL-94 standard, and the sample size was 125×13×3.2mm 3 Cone calorimetry test results are based on ISO 5660, with a sample size of 100×100×3 mm3 and a heat flux of 50 kW / m 2 ). The test results are shown in Table 1:

[0045] Table 1 Flame retardant properties of epoxy resin composites

[0046]

[0047] As can be seen from Table 1, the epoxy resin composite material obtained by using the functional flame retardant prepared in the embodiment of the present invention exhibits excellent flame retardancy and smoke suppression performance, and more importantly, it passes the V-0 grade of the UL-94 test.

[0048] The prepared epoxy resin composite material was tested for UV-visible absorption spectrum (sample size: 100×50×2mm 3 ), the test results are shown in Table 2:

[0049] Table 2 UV transmittance of epoxy resin composite materials

[0050]

[0051] As can be seen from Table 2, the epoxy resin composite material obtained by using the functional flame retardant prepared in the embodiment of the present invention exhibits excellent ultraviolet protection ability, and the average ultraviolet transmittance in the UVA region and the UVB region is about 0.01%.

[0052] The mechanical properties of the prepared epoxy resin composite material were tested (the mechanical properties were obtained according to GB / T1040.1-2018 and GB / T9341-2008, wherein the tensile test had a tensile rate of 2 mm / min, a gauge length of 50 mm, a width of 10 mm, a thickness of 3 mm, and a dumbbell-shaped sample; the bending test had a sample size of 100 × 15 × 4 mm). 3 , test speed is 2mm / min), the test results are shown in Table 3:

[0053] Table 3 Mechanical properties of epoxy resin composites

[0054]

[0055] It can be seen from Table 3 that the epoxy resin composite material obtained by using the functional flame retardant prepared in the embodiment of the present invention has excellent mechanical properties, with a tensile strength of nearly 70 MPa and a flexural strength of nearly 90 MPa.

[0056] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A zeolite imidazolate framework open nanostructured functional flame retardant, characterized by: The flame retardant is a zeolite imidazolate framework grafted with a ferrocene polymer network. The zeolite imidazolate framework grafted with a ferrocene polymer network has micropores, mesopores and macropores. The micropore size is 1.5-2.5nm, the mesopore size is 30-50nm, and the macropore size is 70-120nm. The preparation method of the zeolite imidazolate framework open nanostructure functional flame retardant comprises the following steps: In the first step, the aminated zeolite imidazolate framework is dispersed in methanol to obtain a dispersion; In the second step, a methanol solution of ferrocenecarboxaldehyde is added to the dispersion obtained in the first step, and the mixture is heated to react at a temperature of 55-65°C for 12-24 hours. After the reaction is completed, the mixture is cooled to room temperature and centrifuged. The filter cake is washed and then dried in an oven at 50-60°C for 12-24 hours to obtain a solid. In the third step, the solid obtained in the second step is dispersed in 1,2-dichloroethane, and then a 1,2-dichloroethane solution of ferrocene, dimethylformal, and boron trifluoride ether are added, and the mixture is reacted at 70-80°C for 4-5 hours. After the reaction is completed, the mixture is cooled to room temperature and centrifuged. The filter cake is washed and then dried in an oven at 50-60°C for 12-24 hours to obtain a zeolite imidazole ester framework open nanostructured functional flame retardant.

2. A method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant, the method comprising the steps of: In the first step, the aminated zeolite imidazolate framework is dispersed in methanol to obtain a dispersion; In the second step, a methanol solution of ferrocenecarboxaldehyde is added to the dispersion obtained in the first step, and the mixture is heated to react at a temperature of 55-65°C for 12-24 hours. After the reaction is completed, the mixture is cooled to room temperature and centrifuged. The filter cake is washed and then dried in an oven at 50-60°C for 12-24 hours to obtain a solid. In the third step, the solid obtained in the second step is dispersed in 1,2-dichloroethane, and then a 1,2-dichloroethane solution of ferrocene, dimethylformal, and boron trifluoride ether are added, and the mixture is reacted at 70-80°C for 4-5 hours. After the reaction is completed, the mixture is cooled to room temperature and centrifuged. The filter cake is washed and then dried in an oven at 50-60°C for 12-24 hours to obtain a zeolite imidazole ester framework open nanostructured functional flame retardant.

3. The method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant according to claim 2, characterized in that: In the first step, the ratio of the aminated zeolite imidazolate framework to methanol is 0.5 g: 50-100 ml.

4. The method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant according to claim 2, characterized in that: In the second step, the ratio of ferrocenecarboxaldehyde to methanol in the methanol solution of ferrocenecarboxaldehyde is 0.5 g: 50-100 ml.

5. The method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant according to claim 2, characterized in that: In the second step, the ratio of ferrocenecarboxaldehyde to the aminated zeolitic imidazolate framework is 1 g:0.5-1.5 g.

6. The method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant according to claim 2, characterized in that: In the third step, the solid obtained in the second step is dispersed in 1,2-dichloroethane at a ratio of 0.5 g of the solid to 1,2-dichloroethane: 100-150 ml.

7. The method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant according to claim 2, characterized in that: In the third step, the ratio of ferrocene to 1,2-dichloroethane in the ferrocene-1,2-dichloroethane solution is 1 g: 100-150 ml.

8. The method for preparing a zeolite imidazolate framework open nanostructured functional flame retardant according to claim 2, characterized in that: In the third step, the ratio of solid, ferrocene, dimethanol formal, and boron trifluoride etherate is 0.5 g: 0.5-1.5 g: 5-7 g: 2-3 g.

9. Use of the zeolite imidazolate framework open nanostructure functional flame retardant according to claim 1 in epoxy resin, characterized in that The steps are: The ethanol dispersion of the zeolite imidazole ester framework open nanostructure functional flame retardant, epoxy resin and curing agent are stirred and mixed, and then the temperature is increased for curing to obtain the epoxy resin composite material.

10. Use of a zeolite imidazolate framework open nanostructured functional flame retardant in epoxy resin according to claim 9, characterized in that: In the ethanol dispersion of the zeolite imidazolate framework open nanostructure functional flame retardant, the ratio of the zeolite imidazolate framework open nanostructure functional flame retardant to ethanol is 5g:5-15ml; The curing agent is 4,4-diphenyl diphenyl sulfone; The ratio of the zeolite imidazolate framework open nanostructure functional flame retardant, epoxy resin and curing agent is 5g:50-100g:25-35g; The model of the epoxy resin is E-44 epoxy resin; The curing temperature is 170-180℃ and the curing time is 3-4h.

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