CN114380839A

CN114380839A - Zinc-porphyrin complex and preparation method and application thereof

Info

Publication number: CN114380839A
Application number: CN202210092540.1A
Authority: CN
Inventors: 杨伟; 周宇; 朱三娥; 卫春祥; 鲁红典
Original assignee: Hefei University
Current assignee: Hefei University
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2022-04-22

Abstract

The invention relates to a zinc-porphyrin complex and a preparation method and application thereof. Then zinc acetate is used to react with the zinc acetate to obtain a zinc-porphyrin complex, and finally the high molecular composite material is prepared by a melt blending method. The zinc-porphyrin complex has good compatibility with a high polymer material, and has strong pi-pi interaction force with the high polymer material, so that the mechanical property of the high polymer material can be effectively improved. The zinc-porphyrin complex has better ultraviolet absorption and free radical capture functions, and can effectively improve the anti-photoaging performance of the high polymer material; the thermal stability is excellent, and the thermal stability of the high polymer material in a nitrogen and air atmosphere can be obviously improved; has better flame retardant property, and can effectively inhibit the heat release and the release of toxic and asphyxiant gases when the high polymer material is burnt.

Description

Zinc-porphyrin complex and preparation method and application thereof

Technical Field

The invention belongs to the technical field of metal organic complexes, and particularly relates to a zinc-porphyrin complex and a preparation method and application thereof.

Background

Polystyrene (PS) is widely used in the fields of construction, packaging, electronics, and the like because of its advantages of low density, excellent chemical resistance, and easy processing. PS still has some drawbacks that limit its further development and application: (1) the mechanical property is poor. The main chain of the PS is a saturated carbon chain, and the side group is a conjugated benzene ring, so that the PS is an amorphous linear polymer. The presence of the benzene ring makes PS have stronger rigidity and is easy to crack due to stress, so the toughness is poorer. (2) The aging resistance is poor. PS is very sensitive to ultraviolet rays, molecular chains can be broken after the PS is irradiated by the ultraviolet rays, the mechanical property of the PS is seriously influenced, and the service life of the PS is shortened. (3) And (4) combustibility. PS is extremely easy to burn, and releases a large amount of heat and CO during burning₂And the like, which are toxic and asphyxia gases, endanger the life of people.

Aiming at the three defects of the polystyrene PS, an ultraviolet absorber, a flame retardant, a toughening agent and the like are required to be added respectively to improve the comprehensive performance of the PS at present. For example, chinese patent CN 110746712a adds an organic rare earth composite stabilizer to improve the anti-photoaging performance of PS. A macromolecular nitrogen-halogen flame retardant prepared by Chinese patent CN 113736202A is used for improving the flame retardant property of PS, and the prepared composite material has an oxygen index of more than 46 percent and good smoke suppression property. Chinese patent CN 101967249a reports a modified polyvinyl butyral for improving the toughness of PS while maintaining the rigidity of PS. However, most additives have poor thermal stability, and the addition of PS reduces the thermal stability. In addition, at present, no multifunctional additive capable of improving the ageing resistance, the mechanical property, the flame retardant property and the thermal stability of polystyrene is available.

Porphyrin as a heterocyclic compound has good biocompatibility and is widely applied to the fields of biology, catalysis and the like. In addition, porphyrin has good thermal stability and ultraviolet absorptivity, the end group of porphyrin can be connected with different groups, and the middle cavity can be coordinated with metal to form a complex. Therefore, based on the excellent properties and special structure of porphyrin, a multifunctional metal-porphyrin complex is developed to improve the thermal stability, aging resistance, mechanical properties and flame retardant property of Polystyrene (PS), which is a hotspot and difficulty in the field of research and development of the existing polymer multifunctional additive.

Disclosure of Invention

The invention aims to overcome the defects of the existing polystyrene and provides a zinc-porphyrin complex and a preparation method and application thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a zinc-porphyrin complex has a chemical structural formula as follows:

the invention provides a preparation method of the zinc-porphyrin complex, which comprises the following steps:

1) firstly, mixing propionic acid and propionic anhydride in proportion, then adding p-bromobenzaldehyde, mixing and dissolving;

2) slowly adding a mixed solution of propionic acid and pyrrole into the solution obtained in the step 1), and dropwise adding the mixed solution to finish the heat preservation reaction;

3) washing the product after the reaction in the step 2), removing the solvent, purifying and drying to obtain dark purple powder, namely the m-tetra (p-bromophenyl) porphyrin crystal (BrTPP);

4) reacting the m-tetra (p-bromophenyl) porphyrin crystal (BrTPP) obtained in the step 3) with zinc acetate to obtain the zinc-porphyrin complex (ZnBrTPP).

As a preferred technical scheme of the preparation method, the preparation method comprises the following steps:

adding p-bromobenzaldehyde in the step 1), introducing nitrogen gas at room temperature for protection, and mixing for 30-45 min until the p-bromobenzaldehyde is completely dissolved. The molar ratio of the propionic anhydride to the propionic acid is 2.5-3.5: 1.

In the step 2), the solution in the step 1) is stirred at 140-160 ℃, meanwhile, the mixed solution of propionic acid and pyrrole is slowly added, a condenser pipe is added after the dropwise addition is finished, and the reaction is continued for 3-4 hours at 140-160 ℃. The molar ratio of the p-bromobenzaldehyde added in the step 1) to the pyrrole added in the step 2) is 1: 1-1.2.

And 4) mixing the m-tetra (p-bromophenyl) porphyrin crystal (BrTPP) and zinc acetate, adding an organic solvent, and reacting for 10-15 hours in a water bath at the temperature of 55-65 ℃ to obtain the zinc-porphyrin complex (ZnBrTPP). The molar ratio of the m-tetra (p-bromophenyl) porphyrin crystal (BrTPP) to the zinc acetate is 1: 1.4-1.6, and the organic solvent is dichloromethane, ethyl acetate or tetrahydrofuran.

The invention also provides application of the porphyrin or zinc-porphyrin complex prepared by the method as a high polymer material multifunctional additive, and particularly relates to a composite material prepared by melt blending of the porphyrin or zinc-porphyrin complex and a high polymer material, wherein the mass percentage of the porphyrin or zinc-porphyrin in the prepared composite material is 5-10%.

As a preferred technical scheme of the application, the step of preparing the composite material by melt blending comprises the following steps:

1.5-3 g of porphyrin (BrTPP) or zinc-porphyrin complex (ZnBrTPP) and 27-28.5 g of Polystyrene (PS) are taken and melt-blended for 20-30 min at 185-190 ℃, and then the BrTPP/PS or ZnBrTPP/PS composite material is obtained.

The invention mainly takes p-bromobenzaldehyde and pyrrole as raw materials to synthesize porphyrin, and obtains m-tetra (p-bromophenyl) porphyrin crystal (BrTPP) after purification. Then zinc acetate reacts with the synthesized m-tetra (p-bromophenyl) porphyrin crystal to obtain the zinc-porphyrin complex (ZnBrTPP) of the invention, and finally the high molecular composite material is prepared by a melt blending method. Compared with the prior art, the invention has the following advantages:

1) the zinc-porphyrin complex has good compatibility with a high polymer material (taking polystyrene as an example), and has stronger pi-pi interaction force with the high polymer material, so that the mechanical property of the high polymer material can be effectively improved.

2) The zinc-porphyrin complex has good ultraviolet absorption and free radical capture functions, and can effectively improve the light aging resistance of the high polymer material.

3) The zinc-porphyrin complex has excellent thermal stability, and can remarkably improve the thermal stability of a high polymer material in a nitrogen and air atmosphere.

4) The zinc-porphyrin complex has good flame retardant property, and can effectively inhibit the heat release and the release of toxic and asphyxiant gases during the combustion of high polymer materials.

5) The zinc-porphyrin complex has the advantages of simple preparation method, higher yield, relatively lower cost and wide application prospect.

Drawings

FIG. 1 shows the NMR spectra of the target products (porphyrin (bottom) and zinc-porphyrin complex (top)) prepared in examples 1 and 5.

FIG. 2 shows the thermal decomposition curves of the target products (porphyrin and zinc-porphyrin complex, respectively) prepared in examples 1 and 5.

FIG. 3 is a graph showing the tensile properties of the target products of the composite materials prepared in examples 6 to 9.

FIG. 4 is a graph showing the tensile properties of the target products of the composite materials prepared in examples 6 to 9 after ultraviolet light aging.

FIG. 5 is a thermogravimetric analysis (TGA) curve (a) and a mass loss rate (DTG) curve (b) of a target product of a composite material prepared in examples 6-9 under a nitrogen atmosphere.

FIG. 6 is a graph (a) showing the thermogravimetric curves (a) and the mass loss rates (DTG) of the target products of the composite materials prepared in examples 6 to 9 under the air atmosphere.

FIG. 7 is a graph of the combustion performance of target products for composites prepared in examples 7 and 9, including the Heat Release Rate (HRR) (a), Total Heat Release (THR) (b), and CO₂Gas release profiles (c, d).

Detailed Description

The zinc-porphyrin complex of the present invention, the preparation method and the application thereof are further described in detail with reference to the following examples and the accompanying drawings.

Example 1

1) Dissolving 5g of p-bromobenzaldehyde in 300mL of propionic acid-propionic anhydride mixed solvent (the molar ratio of propionic acid to propionic anhydride is 3: 1) at room temperature, stirring in nitrogen atmosphere to accelerate dissolution for 30min, and dissolving completely.

2) Transferring the solution obtained in the step 1) into a 150 ℃ oil bath kettle, preheating for a period of time, slowly dropwise adding a mixed solution of 10mL of propionic acid and 2g of pyrrole while stirring, adding a condenser pipe after dropwise adding, and continuously reacting for 3 hours at 150 ℃.

3) Adding pure water into the solution which is reacted in the step 2) for precipitation, filtering the obtained product to remove the precipitate, washing the product to completely remove the solvent, purifying and drying the product to obtain the dark purple powder which is porphyrin crystal BrTPP (yield: 15%).

Nuclear magnetic resonance hydrogen spectrum of porphyrin in figure 1¹H NMR (400MHz, deuterated chloroform) was specifically analyzed as follows (δ, ppm): chemical shifts in porphyrin rings are 8.83-8.87, -2.28-2.25, and chemical shifts of hydrogen on benzene rings are 8.08-8.10 and 7.89-7.93.

Example 2

1) 5g of p-bromobenzaldehyde is dissolved in 300mL of propionic acid-propionic anhydride mixed solvent (the molar ratio of propionic acid to propionic anhydride is 2.8: 1) at room temperature, and the mixture is stirred and dissolved for 35min at an accelerated speed under the nitrogen atmosphere until the mixture is completely dissolved.

2) Transferring the solution obtained in the step 1) into an oil bath kettle at 140 ℃, preheating for a period of time, slowly dropwise adding a mixed solution of 10mL of propionic acid and 2.2g of pyrrole while stirring, adding a condenser after dropwise adding, and continuously reacting for 3.5h at 140 ℃.

3) Adding pure water into the solution obtained after the reaction in the step 2) for precipitation, filtering the obtained product to remove the precipitate, washing the product to completely remove the solvent, and purifying and drying the product to obtain dark purple powder, namely porphyrin crystal BrTPP (yield: 16%).

Example 3

1) Dissolving 5g of p-bromobenzaldehyde in 300mL of propionic acid-propionic anhydride mixed solvent (the molar ratio of propionic acid to propionic anhydride is 3.2: 1) at room temperature, and stirring under nitrogen atmosphere to accelerate dissolution for 40min until the p-bromobenzaldehyde is completely dissolved.

2) Transferring the solution obtained in the step 1) into a 160 ℃ oil bath kettle, preheating for a period of time, slowly dropwise adding a mixed solution of 10mL of propionic acid and 1.92g of pyrrole while stirring, adding a condenser pipe after dropwise adding, and continuously reacting for 4 hours at 160 ℃.

3) Adding pure water into the solution obtained after the reaction in the step 2) for precipitation, filtering the obtained product to remove the precipitate, washing the product to completely remove the solvent, and purifying and drying the product to obtain dark purple powder, namely porphyrin crystal BrTPP (yield: 20%).

Example 4

1) Dissolving 5g of p-bromobenzaldehyde in 300mL of propionic acid-propionic anhydride mixed solvent (the molar ratio of propionic acid to propionic anhydride is 2.5: 1) at room temperature, stirring and accelerating the dissolution for 45min under a nitrogen atmosphere, and completely dissolving.

2) Transferring the solution obtained in the step 1) into a 150 ℃ oil bath kettle, preheating for a period of time, slowly dropwise adding a mixed solution of 10mL of propionic acid and 2.05g of pyrrole while stirring, adding a condenser pipe after dropwise adding, and continuously reacting for 4 hours at 150 ℃.

3) Adding pure water into the solution obtained after the reaction in the step 2) for precipitation, filtering the obtained product to remove the precipitate, washing the product to completely remove the solvent, and purifying and drying the product to obtain dark purple powder, namely porphyrin crystal BrTPP (yield: 22%).

Example 5

2g of porphyrin crystal obtained in example 1 is taken and dissolved in 200mL of dichloromethane, 0.6g of zinc acetate is added, the mixture reacts overnight for more than 12h under the condition of heating in water bath at 60 ℃, and bright purple powder is obtained through suction filtration, extraction and drying, namely the zinc-porphyrin complex ZnBrTPP (yield: 95%).

Nuclear magnetic resonance hydrogen spectrum of zinc-porphyrin complex in figure 1¹H NMR (400MHz, deuterated chloroform) was specifically analyzed as follows (δ, ppm): chemical shifts in porphyrin rings are 8.83-8.87, and chemical shifts of hydrogen on benzene rings are 8.08-8.10 and 7.89-7.93. Wherein the chemical shift at the-2.28 to-2.25 position disappears due to successful coordination of zinc.

Example 6

The porphyrin crystal (BrTPP) prepared in example 1 is mixed with PS according to the mass percent of 5%, the mixed material is added into an internal mixer for internal mixing, the internal mixing temperature is 185 ℃, the mixing time is 20min, then the mixture is pressed into a test sample strip through a die, and the composite material is marked as 5 BrTPP/PS.

Example 7

The porphyrin crystal (BrTPP) prepared in the example 1 is mixed with PS according to the mass percentage of 10%, the mixed material is added into an internal mixer for internal mixing, the internal mixing temperature is 190 ℃, the time is 30min, then the mixture is pressed into a test sample strip through a die, and the composite material is marked as 10 BrTPP/PS.

Example 8

The zinc-porphyrin complex (ZnBrTPP) prepared in example 5 is mixed with PS according to the mass percent of 5 percent, the mixed material is added into an internal mixer for internal mixing, the internal mixing temperature is 190 ℃, the time is 20min, and then the mixture is pressed into a test sample strip through a die, wherein the mark of the composite material is 5 ZnBrTPP/PS.

Example 9

The zinc-porphyrin complex (ZnBrTPP) prepared in example 5 is mixed with PS according to the mass percent of 10 percent, the mixed material is added into an internal mixer for internal mixing, the internal mixing temperature is 187 ℃, the time is 25min, and then the mixture is pressed into a test sample strip through a die, and the composite material is marked as 10 ZnBrTPP/PS.

Comparative example 1

And (3) carrying out internal mixing on pure polystyrene in an internal mixer at the temperature of 190 ℃ for 30min to obtain a blended sample, and then pressing the blended sample into a test sample strip through a die, wherein the material is marked as PS.

FIG. 2 is a graph of the thermal decomposition of BrTPP and ZnBrTPP, from which it can be seen that the thermal decomposition temperature of BrTPP is 515 deg.C, while that of ZnBrTPP is raised to 539 deg.C, indicating that the introduction of metal enhances the thermal stability of the porphyrin and, therefore, the thermal stability of the PS can be further enhanced.

FIG. 3 and Table 1 show the tensile property test curves and the average pull-up property parameters for PS and its composites. As can be seen from FIG. 3 and Table 1, the tensile strength of PS is 89.4MPa and the elongation at break is 6.4%. With the introduction of BrTPP and ZnBrTPP, the mechanical property of PS is improved, and particularly, the tensile strength of the PS composite material added with 5 percent of ZnBrTPP is improved by 102.2MPa, the elongation at break is improved to 12.6 percent, and the mechanical property of PS is obviously improved by the addition of ZnBrTPP.

TABLE 1

Fig. 4 and table 1 demonstrate the change in mechanical properties of PS and its composites after 100h uv aging. The test conditions of ultraviolet light aging are as follows: a 500W ultraviolet lamp, the testing time is 100h, the temperature is 30 ℃, the humidity is 100%, the distance between a sample and a light source is 20cm, and the wavelength of light is 302 nm. It can be seen from fig. 4 and table 1 that after 100h of uv light aging, the mechanical property of pure PS is reduced significantly, and the mechanical property reduction amplitude is greatly reduced after adding porphyrin or zinc-porphyrin complex, wherein the mechanical property of 5BrTPP/PS sample is hardly reduced, which indicates that the uv light aging resistance of PS can be effectively improved by adding porphyrin or zinc-porphyrin complex.

Fig. 5 is a TGA curve and a DTG curve of the prepared PS and its composite material under nitrogen, and the related data are shown in table 2. As can be seen from FIG. 5, the addition of zinc-porphyrin complex can effectively improve the thermal stability of PS, wherein the thermal decomposition temperature (T) of PS can be adjusted by 5% of the addition amount_-5％) The temperature is raised to 415 ℃. FIG. 6 is a TGA curve and a DTG curve of PS and its composite material under air condition, and it can be seen from FIG. 6 that the thermal decomposition temperature (T) of PS is 5% by mass after adding zinc-porphyrin complex_-5％) The temperature is improved by 79 ℃. This is because the porphyrin itself has a very good thermal stability, which can effectively improve the thermal stability of PS.

TABLE 2

In the table: t is_-5％: weight loss 5% pairThe temperature of reaction; t is_max: the temperature corresponding to the maximum value of the rate of weight loss.

Fig. 7 is a test curve of the combustion performance of the prepared PS and its composite material, including HRR and THR and release of carbon monoxide, carbon dioxide gas, and the related data are summarized in table 3. As can be seen from FIG. 7 and Table 3, pure PS was ignited at 52s, PHRR was 1037.6kW/m²THR is 136.5MJ/m²It is a highly flammable material that generates a large amount of heat during combustion. The addition of BrTPP had no significant effect on the TTI and PHRR of the PS. And the PHRR value of 10ZnBrTPP/PS is obviously reduced (reduced by about 26.0%). At the same time, a reduction in THR was also observed (about 13.2% and 9.4% reduction for 10BrTPP/PS and 10ZnBrTPP/PS, respectively). Furthermore, 10ZnBrTPP/PS showed lower PCOP compared to pure PS and 10 BrTPP/PS. This shows that the addition of the metal element can effectively enhance the CO inhibition effect of the halogen-containing flame retardant. As for CO₂PCO by introducing BrTPP and ZnBrTPP into PS₂The P value is reduced by 10.6 percent and 31.5 percent respectively. The result shows that the addition of ZnBrTPP can effectively inhibit CO and CO₂And the release of gas improves the flame retardant property of PS.

TABLE 3

In the table: TTI: a time of ignition; PHRR: peak heat release rate; THR: total heat release; PCOP: a peak CO production rate; PCO₂P：CO₂A rate peak is generated.

From the comparison between examples 6-9 and the comparative example, it can be seen that the zinc-porphyrin complex (ZnBrTPP) with the addition amount of 5-10% can effectively improve the ultraviolet light aging resistance, the mechanical property, the thermal stability and the flame retardant property of the PS. The zinc-porphyrin complex (ZnBrTPP) is a high-efficiency and low-cost multifunctional additive, and can effectively improve the comprehensive performance of PS so as to expand the application range of PS.

The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.

Claims

1. A zinc-porphyrin complex has a chemical structural formula as follows:

2. a process for preparing the zinc-porphyrin complex of claim 1, comprising the steps of:

3. The method as claimed in claim 2, wherein p-bromobenzaldehyde is added in the step 1), and then nitrogen is introduced at room temperature for 30-45 min for mixing until complete dissolution.

4. The process according to claim 2, wherein the molar ratio of propionic anhydride to propionic acid in step 1) is 2.5 to 3.5: 1.

5. The method of claim 2, wherein in the step 2), the solution in the step 1) is firstly stirred at 140-160 ℃, meanwhile, the mixed solution of propionic acid and pyrrole is slowly added, a condenser tube is added after the dropwise addition, and the reaction is continued for 3-4 h at 140-160 ℃.

6. The method according to claim 2 or 5, wherein the molar ratio of the p-bromobenzaldehyde added in step 1) to the pyrrole added in step 2) is 1: 1 to 1.2.

7. The method of claim 2, wherein in the step 4), the m-tetra (p-bromophenyl) porphyrin crystal (BrTPP) and zinc acetate are mixed, an organic solvent is added, and the mixture is reacted in a water bath at 55-65 ℃ for 10-15 hours to obtain the zinc-porphyrin complex (ZnBrTPP).

8. The method according to claim 2 or 7, wherein the molar ratio of the m-tetrakis (p-bromophenyl) porphyrin crystal (BrTPP) to the zinc acetate is 1: 1.4-1.6, and the organic solvent is dichloromethane, ethyl acetate or tetrahydrofuran.

9. The application of porphyrin or zinc-porphyrin complex prepared by the method of claim 2 as a high polymer material multifunctional additive, wherein the porphyrin or zinc-porphyrin complex and the high polymer material are subjected to melt blending to prepare a composite material, and the mass percentage of the porphyrin or zinc-porphyrin in the prepared composite material is 5-10%.

10. The use of claim 9, wherein the step of melt blending to produce the composite material comprises: 1.5-3 g of porphyrin (BrTPP) or zinc-porphyrin complex (ZnBrTPP) and 27-28.5 g of Polystyrene (PS) are taken and melt-blended for 20-30 min at 185-190 ℃, and then the BrTPP/PS or ZnBrTPP/PS composite material is obtained.