A method for the photocatalytic oxidative degradation of a polymer containing styrene structural units

Abstract

The application discloses a photocatalytic oxidative degradation method of a polymer containing a styrene structural unit. Under the irradiation of a black light, the polymer containing the styrene structural unit is oxidized and degraded by oxygen in air at room temperature through the action of a photosensitizer and an additive, and a benzoic acid product is obtained after a period of reaction. The application has the advantages of mild reaction conditions, good product yield and wide substrate range. The insoluble porphyrin photosensitizer used exhibits excellent activity in the photocatalytic oxidative degradation of the polymer, can generate singlet oxygen in an organic solvent, and can induce the generation of benzyl radicals from the styrene structural unit, so as to initiate the degradation of the polymer containing the styrene structural unit under the action of oxygen in air, and provide a green way for the photocatalytic oxidative degradation of the polymer containing the styrene structural unit.

Description

Technical Field

[0001] This invention relates to a novel method for the photocatalytic oxidation degradation of polymers containing styrene structural units, belonging to the field of photocatalytic polymer degradation technology. Background Technology

[0002] Since the 1950s, synthetic plastics derived from petroleum have been widely used in various fields such as clothing, food preservation, and medical applications. Developing more efficient and low-cost chemical recycling methods for plastics has become a key area of ​​research in chemistry and chemical engineering.

[0003] Polystyrene (PS) is one of the most important materials in the modern plastics industry, widely used in our daily lives, from building materials and electronics to protective packaging and food containers. Because all the atoms in polystyrene are linked by strong C-C and CH bonds, it is highly inert and difficult to degrade without special treatment. Currently, pyrolysis and catalytic pyrolysis have been developed for the chemical recycling of polystyrene under inert or hydrogen atmospheres; however, these technologies require high temperatures, suitable reactors, and catalysts, leading to high costs. Therefore, developing green and efficient methods for polystyrene degradation is of significant research importance.

[0004] Currently, there are relatively few reports on the oxidative degradation of polystyrene. In 1998, Pifer et al. first reported the oxidative degradation of polystyrene (Chemical recycling of plastics to useful organic compounds by oxidative degradation). In 2021, Zeng Rong et al. reported a 67% benzoic acid yield using FeCl3, TBACl, and Cl3CCH2OH as catalysts in an oxygen atmosphere under 390 nm blue light irradiation for 5 days in acetone solution (Photoinduced FeCl3-catalyzed alkyl aromatics oxidation toward degradation of polystyrene at room temperature). In 2022, Li Tengfei et al. reported a 30% benzoic acid yield using fluorenone as a catalyst and H2SO4 as an additive in an oxygen atmosphere under ethyl acetate solution under blue light irradiation for 16 hours (Bridging plastic recycling and organic catalysis: photocatalytic deconstruction of polystyrene via a CH oxidation pathway). In 2022, Xiao Jianliang et al. reported a 51% benzoic acid yield using p-TsOH·H2O as a catalyst in an oxygen atmosphere under blue light irradiation for 15 hours in a mixed solution of benzene and acetonitrile (Chemical recycling of polystyrene to valuable chemicals via selective acid-catalyzed aerobic oxidation under visible light). In 2023, Jiang Xuefeng et al. reported a 30% benzoic acid yield using UO2(NO3)2·6H2O as a catalyst and HCl as an additive in an oxygen atmosphere under blue light irradiation for 72 hours in a dichloromethane solvent (Degradation of plastic wastes to commercial chemicals and monomers under visible light). In addition, there are some reports on the oxidative degradation of polystyrene. However, most of the currently reported polystyrene oxidative degradation is based on photocatalysis using homogeneous small-molecule photosensitizers in organic solvents under oxygen conditions; therefore, it is necessary to develop a heterogeneous high-molecular-weight photosensitizer to achieve efficient photocatalytic oxidative degradation of polystyrene in an air atmosphere.

[0005] This invention uses polymers containing styrene structural units with different weight-average molecular weights, insoluble polyporphyrin as a photosensitizer, and acid as an additive. Under black light (wavelength range of 365-370nm) irradiation conditions, in an organic solvent, in an air atmosphere, and at room temperature, the polymers containing styrene structural units with different weight-average molecular weights are oxidized and degraded to obtain benzoic acid products. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a new method for photocatalytic oxidative degradation of polymers containing styrene structural units.

[0007] The technical solution of the present invention:

[0008] A photocatalytic oxidative degradation method for polymers containing styrene structural units, comprising the following steps:

[0009] In a solvent, using insoluble polyporphyrin P-1 as a photosensitizer and acid as an additive, under black light irradiation (wavelength range 365-370nm), polymers containing styrene structural units are oxidized and degraded by air to produce benzoic acid. The general reaction formula is as follows:

[0010]

[0011] Wherein, 1 is a polymer containing styrene structural units, where x cannot be 0, but y and z can be 0; 2 is benzoic acid; P-1 is an insoluble polyporphyrin-based photosensitizer;

[0012] The polymers containing styrene structural units are different polystyrene with a weight average molecular weight of 65,000-650,000 g / mol, a styrene-butadiene copolymer with a weight average molecular weight of 140,000 g / mol and a styrene mass fraction of 30%, a styrene-acrylonitrile copolymer with a weight average molecular weight of 165,000 g / mol and a styrene mass fraction of 75%, and a styrene-butadiene-acrylonitrile copolymer with a weight average molecular weight of 238,000 g / mol and a styrene mass fraction of 72%.

[0013] There are seven insoluble polyporphyrin-based photosensitizers with different structures, prepared using similar methods. P-1 is prepared by polymerization of 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:2; P-2 is prepared by polymerization of 5,10,15,20-tetra(4-bromophenyl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:2; P-3 is prepared by polymerization of 5,10,15,20-tetra(4-bromophenyl)porphyrin and 1,7-octadiyne in a molar ratio of 1:2; and P-4 is prepared by polymerization of 4,4'-[ P-1 was obtained by self-polymerization of 10,20-bis(4-bromophenyl)-5,15-bis(2-ethynylphenyl)]porphyrin; P-5 was obtained by polymerization of 5,10,15,20-tetra(4-bromo-2,3,5,6-tetrafluorophenyl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:2; P-6 was obtained by polymerization of 5,10,15,20-tetra(4-bromo-3,5-dimethoxyphenyl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:2; P-7 was obtained by polymerization of 5,10,15,20-tetra(9-bromoanthryl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:2; among them, P-1 showed the best results.

[0014] Among them, the insoluble polyporphyrin-based photosensitizer P-1 is prepared by polymerization of 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:2, and its structure is as follows:

[0015]

[0016] The preparation method of insoluble polyporphyrin-based photosensitizer P-1 is as follows:

[0017] In a reaction flask, 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-porphyrin and 1,4-diethynylbenzene were added in a molar ratio of 1:2, along with bis(triphenylphosphine)palladium dichloride and cuprous iodide. The reaction flask was transferred to a glove box, and dimethyl sulfoxide was added as solvent. After complete dissolution, triethylamine was added, and the mixture was stirred at 100°C for 30 min. After the reaction was completed, the product was centrifuged with dichloromethane to precipitate it. After drying, the product was leached with trifluoroacetic acid to remove zinc, yielding the insoluble polyporphyrin-based photosensitizer P-1.

[0018] The reaction was carried out at room temperature for 16-72 hours to obtain benzoic acid.

[0019] The concentration of styrene monomer in the polymer reaction solution containing styrene structural units is 0.05-0.5 M.

[0020] The amount of the insoluble polyporphyrin-based photosensitizer P-1 is 1-10 mol% of the amount of styrene monomer in the polymer containing styrene structural units;

[0021] The additive is one of sulfuric acid, hydrochloric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid monohydrate, zinc chloride, ytterbium trifluoromethanesulfonate, and scandium trifluoromethanesulfonate, and the amount used is 2.5-50 mol% of the styrene monomer in the polymer containing styrene structural units.

[0022] The light source is black light with a wavelength range of 365-370nm and a power of 20W;

[0023] The organic solvent is one of 1,2-dichloroethane, acetone, dimethyl carbonate, and ethyl acetate;

[0024] The post-processing method was as follows: the residual insoluble polyporphyrin P-1 was removed by filtration, the product was dried by rotary evaporation, separated by column chromatography, and then dried to constant weight in a vacuum drying oven.

[0025] The beneficial effects of this invention are as follows: The photocatalytic oxidative degradation method for polymers containing styrene structural units in this invention operates under mild reaction conditions, using oxygen from the air for oxidation. In an organic solvent, polymers containing styrene structural units of varying weight-average molecular weights can be oxidized and degraded to benzoic acid, with good product yields and a broad substrate range. The insoluble polyporphyrin-based photosensitizer used exhibits excellent photocatalytic activity, providing a green pathway for the photocatalytic oxidative degradation of polymers containing styrene structural units. Attached Figure Description

[0026] Figure 1 This is a SEM image of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of the present invention. The scale bar is 1 μm.

[0027] Figure 2 This is a TGA image of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of the present invention;

[0028] Figure 3 The image shows the XRD pattern of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of this invention.

[0029] Figure 4 (a) is the nitrogen adsorption-desorption isotherm of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of the present invention. Figure 4 (b) is a pore size distribution diagram of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of the present invention;

[0030] Figure 5 This is the UV-Vis spectrum (solid UV) of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Example 1:

[0034] Preparation of insoluble polyporphyrin-based photosensitizer P-1

[0035] 1) Pyrrole (2 mL, 30 mmol) and 4-bromobenzaldehyde (5 g, 30 mmol) were dissolved in a mixture of propionic acid (45 mL) and acetic acid (15 mL), stirred at 120 °C for 2 h, cooled to room temperature, washed with acetic acid and methanol and dried to obtain 5,10,15,20-tetra(4-bromophenyl)porphyrin (1) (5.65 g, 90%).

[0036] 2) Under N2 protection, 5,10,15,20-tetratetra(4-bromophenyl)porphyrin (1) (400 mg, 0.43 mmol), anhydrous potassium carbonate (6.4 mmol, 890 mg), and 50 mL of pyridine were mixed in a three-necked flask. After all solids dissolved, p-toluenesulfonyl hydrazine (4.3 mmol, 800 mg) was added. The reaction mixture was stirred in the dark and refluxed at 105 °C for 20 hours. After reflux, an equal volume of p-toluenesulfonyl hydrazine (4.3 mmol, 800 mg) was added to the three-necked flask under N2 protection, and the mixture was stirred at room temperature in the dark for 8 hours. Then, 50 mL of benzene and 50 mL of deionized water were added to the three-necked flask, and the mixture was refluxed for 1 hour. After cooling, the organic phase was washed once with HCl (2M), twice with 68% phosphoric acid, once with deionized water, once with saturated sodium bicarbonate solution, dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The phase was then separated by column chromatography to obtain 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-porphyrin (2) (200 mg, 50%).

[0037] 3) Add 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-porphyrin (2) (200 mg, 0.21 mmol), anhydrous zinc acetate (200 mg, 1.05 mmol), and DMF (3 mL) to the reaction flask. Stir at 120 °C for 3 h. After the reaction is complete, wash three times with deionized water by centrifugation and dry to obtain 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-zinc porphyrin (2-Zn) (198 mg, 93%).

[0038] 4) In a 10 ml reaction flask, add 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-zinc porphyrin (2-Zn) (150 mg, 0.15 mmol), 1,4-diethynylbenzene (38 mg, 0.3 mmol), bis(triphenylphosphine)palladium dichloride (42 mg, 0.06 mmol), and cuprous iodide (5.7 mg, 0.03 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml). After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-1 (117 mg, 85%).

[0039]

[0040] Note: Polyporphyrin P-1 is insoluble in almost all organic and inorganic solvents, including dichloromethane, acetone, methanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, water, etc.

[0041] IR(KBr)v[cm -1 ]:3600-3000(br),2200,1596,1481,1344.

[0042] SEM image of P-1 is shown below. Figure 1 The TGA chart for P-1 is shown below. Figure 2 The XRD pattern of P-1 is shown below. Figure 3 The nitrogen adsorption-desorption isotherm diagram for P-1 is shown below. Figure 4 (a), the pore size distribution diagram of P-1 is shown in [reference needed]. Figure 4 (b) The UV-Vis spectrum of P-1 (solid UV) is shown below. Figure 5 The metal ion residues of P-1 are shown in Table 1.

[0043] Table 1 shows the metal ion residues of the insoluble polyporphyrin-based photosensitizer P-1 in Example 1 of this invention.

[0044]

[0045] Example 2:

[0046] Preparation of insoluble polyporphyrin-based photosensitizer P-2

[0047] 1) Pyrrole (2 mL, 30 mmol) and 4-bromobenzaldehyde (5 g, 30 mmol) were dissolved in a mixture of propionic acid (45 mL) and acetic acid (15 mL), stirred at 120 °C for 2 h, cooled to room temperature, washed with acetic acid and methanol and dried to obtain 5,10,15,20-tetra(4-bromophenyl)porphyrin (1) (5.65 g, 90%).

[0048] 2) Add 5,10,15,20-tetra(4-bromophenyl)porphyrin (1) (280 mg, 0.3 mmol), anhydrous zinc acetate (275 mg, 1.5 mmol) and DMF (3 mL) to the reaction flask, stir at 120 °C for 3 h, and after the reaction is complete, wash three times with deionized water by centrifugation and dry to obtain 5,10,15,20-tetra(4-bromophenyl)zincporphyrin (1-Zn) (268 mg, 90%).

[0049] 3) In a 10 ml reaction flask, add 5,10,15,20-tetratetra(4-bromophenyl)zinc porphyrin (1-Zn) (150 mg, 0.15 mmol), 1,4-diethynylbenzene (38 mg, 0.3 mmol), bis(triphenylphosphine)palladium dichloride (42 mg, 0.06 mmol), and cuprous iodide (5.7 mg, 0.03 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml) to dissolve the product. After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-2 (117 mg, 85%).

[0050]

[0051] Example 3:

[0052] Preparation of insoluble polyporphyrin-based photosensitizer P-3

[0053] 1) Pyrrole (2 mL, 30 mmol) and 4-bromobenzaldehyde (5 g, 30 mmol) were dissolved in a mixture of propionic acid (45 mL) and acetic acid (15 mL), stirred at 120 °C for 2 h, cooled to room temperature, washed with acetic acid and methanol and dried to obtain 5,10,15,20-tetra(4-bromophenyl)porphyrin (1) (5.65 g, 90%).

[0054] 2) Add 5,10,15,20-tetra(4-bromophenyl)porphyrin (1) (280 mg, 0.3 mmol), anhydrous zinc acetate (275 mg, 1.5 mmol) and DMF (3 mL) to the reaction flask, stir at 120 °C for 3 h, and after the reaction is complete, wash three times with deionized water by centrifugation and dry to obtain 5,10,15,20-tetra(4-bromophenyl)zincporphyrin (1-Zn) (268 mg, 90%).

[0055] 3) In a 10 ml reaction flask, add 5,10,15,20-tetratetra(4-bromophenyl)zinc porphyrin (1-Zn) (150 mg, 0.15 mmol), 1,7-octadiyne (32 mg, 0.3 mmol), bis(triphenylphosphine)palladium dichloride (42 mg, 0.06 mmol), and cuprous iodide (5.7 mg, 0.03 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml) to dissolve the product. After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-3 (105 mg, 85%).

[0056]

[0057] Example 4:

[0058] Preparation of insoluble polyporphyrin-based photosensitizer P-4

[0059] 1) In a 25 mL reaction flask, add pyrrole (5 mL, 75 mmol) and 4-bromobenzaldehyde (5 g, 30 mmol), then add trifluoroacetic acid (0.1 mL, 1.3 mmol). Evacuate the reaction flask, purge with nitrogen, heat to 40 °C, and stir the reaction. Purify by column chromatography to obtain 2,2'-[(4-bromophenyl)methylene]bis(1H-pyrrole)(1) (6.5 g, 80%).

[0060] 2) 4-ethynyltrimethylsilylbenzaldehyde (1.205 g, 5.5 mmol) and 2,2'-[(4-bromophenyl)methylene]bis(1H-pyrrole) (1 g, 5.5 mmol) were added to a 250 mL round-bottom flask, followed by trifluoroacetic acid (170 μL, 3 mmol) and 160 mL dichloromethane (DCM). The round-bottom flask was evacuated and purged with nitrogen. The mixture was stirred at room temperature for 3 hours, and then 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) (2.724 g, 16.5 mmol) was added, and the reaction was allowed to proceed for 30 minutes. The solvent was removed by rotary evaporation, and the mixture was purified by column chromatography to obtain 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynyltrimethylsilylphenyl)]porphyrin (2) (635 mg, 24%).

[0061] 3) Add 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynyltrimethylsilylphenyl)]porphyrin (2) (400 mg, 0.4 mmol) and THF (8 mL) to the reaction flask, stir to dissolve, then add ethanol solution (6 mL), deionized water (4 mL), and sodium hydroxide (80 mg, 2 mmol), and stir overnight at 65 °C. After the reaction is complete, adjust the pH of the system to 5-6 with 1 M hydrochloric acid solution, filter, and dry to obtain 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynylphenyl)]porphyrin (3) (296 mg, 90%).

[0062] 4) 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynylphenyl)]porphyrin (3) (200 mg, 0.24 mmol), anhydrous zinc acetate (220 mg, 1.2 mmol) and DMF (3 mL) were stirred at 120 °C for 3 h. After the reaction was completed, the mixture was washed three times by centrifugation with deionized water and dried to obtain 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynylphenyl)]zinc porphyrin (3-Zn) (191 mg, 90%).

[0063] 5) In a 10 ml reaction flask, add 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynylphenyl)]zinc porphyrin (3-Zn) (150 mg, 0.17 mmol), 1,4-diethynylphenyl (43 mg, 0.34 mmol), bis(triphenylphosphine)palladium dichloride (48 mg, 0.068 mmol), and cuprous iodide (6.5 mg, 0.034 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml). After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-5 (114 mg, 85%).

[0064]

[0065] Example 5:

[0066] Preparation of insoluble polyporphyrin-based photosensitizer P-5

[0067] 1) Pyrrole (270 μL, 3.9 mmol) and 4-bromo-2,3,5,6-tetrafluorobenzaldehyde (1 g, 3.9 mmol) were dissolved in a mixture of propionic acid (45 mL) and acetic acid (15 mL). The mixture was stirred at 120 °C for 2 h. After cooling to room temperature, the solvent was removed by rotary evaporation. The solvent was separated by column chromatography to obtain 5,10,15,20-tetra(4-bromo-2,3,5,6-tetrafluorophenyl)porphyrin (1) (270 mg, 23%).

[0068] 2) Add 5,10,15,20-tetratetra(4-bromo-2,3,5,6-tetrafluorophenyl)porphyrin (1) (200 mg, 0.16 mmol), anhydrous zinc acetate (150 mg, 0.8 mmol) and DMF (3 mL) to the reaction flask, stir at 120 °C for 3 h, and after the reaction is completed, wash three times with deionized water by centrifugation and dry to obtain 5,10,15,20-tetratetra(4-bromo-2,3,5,6-tetrafluorophenyl)zincporphyrin (1-Zn) (190 mg, 90%).

[0069] 3) In a 10 ml reaction flask, add 5,10,15,20-tetratetra(4-bromo-2,3,5,6-tetrafluorophenyl)zinc porphyrin (1-Zn) (150 mg, 0.12 mmol), 1,4-diethynylbenzene (30 mg, 0.24 mmol), bis(triphenylphosphine)palladium dichloride (34 mg, 0.048 mmol), and cuprous iodide (4.6 mg, 0.024 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml). After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-5 (117 mg, 85%).

[0070]

[0071] Example 6:

[0072] Preparation of insoluble polyporphyrin-based photosensitizer P-6

[0073] 1) Pyrrole (139 μL, 2 mmol) and 4-bromo-3,5-dimethoxybenzaldehyde (490 mg, 2 mmol) were dissolved in a mixture of propionic acid (45 mL) and acetic acid (15 mL). The mixture was stirred at 120 °C for 2 h. After cooling to room temperature, the solvent was removed by rotary evaporation. Column chromatography was used to separate 5,10,15,20-tetrakis(4-bromo-3,5-dimethoxyphenyl)porphyrin (1) (252 mg, 43%).

[0074] 2) Add 5,10,15,20-tetrakis(4-bromo-3,5-dimethoxyphenyl)porphyrin (1) (200 mg, 0.17 mmol), anhydrous zinc acetate (156 mg, 0.85 mmol), and DMF (3 mL) to the reaction flask. Stir at 120 °C for 3 h. After the reaction is complete, wash three times with deionized water by centrifugation and dry to obtain 5,10,15,20-tetrakis(4-bromo-3,5-dimethoxyphenyl)zinc porphyrin (1-Zn) (198 mg, 94%).

[0075] 3) In a 10 ml reaction flask, add 5,10,15,20-tetratetra(4-bromo-3,5-dimethoxyphenyl)zinc porphyrin (1-Zn) (150 mg, 0.12 mmol), 1,4-diethynylbenzene (30 mg, 0.24 mmol), bis(triphenylphosphine)palladium dichloride (34 mg, 0.048 mmol), and cuprous iodide (4.6 mg, 0.024 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml). After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-6 (112 mg, 85%).

[0076]

[0077] Example 7:

[0078] Preparation of insoluble polyporphyrin-based photosensitizer P-7

[0079] 1) Add 9,10-dibromoanthracene (3 g, 8.9 mmol) to a reaction flask, followed by 15 mL of dry diethyl ether. Transfer the flask to a glove box and add n-butyllithium (2 M in n-hexane, 4.5 mL, 9 mmol). Stir the mixture at room temperature for 30 minutes. Then, add 3.5 mL of diethyl ether solution of pyrrole-2-carboxaldehyde (428 mg, 4.5 mmol) and stir the mixture at room temperature for 1 hour. Pour the reaction mixture into an ice-cold saturated NH4Cl solution (30 mL), separate the organic phase, wash with water (3 × 30 mL), and dry with anhydrous Na2SO4. Remove the solvent by rotary evaporation. Transfer the intermediate crude product to a boiling solution of propionic acid (25 mL), stir and reflux at 140 °C for 3 hours, then cool and let stand overnight. Filter the resulting black viscous mixture through filter paper and wash with methanol until a clear solution is obtained. The collected precipitate was separated by column chromatography to obtain 5,10,15,20-tetra(9-bromoanthryl)porphyrin (1) (215 mg, 15%).

[0080] 2) Add 5,10,15,20-tetra(9-bromoanthryl)porphyrin (1) (200 mg, 0.15 mmol), anhydrous zinc acetate (138 mg, 0.75 mmol) and DMF (3 mL) to the reaction flask, stir at 120 °C for 3 h, and after the reaction is complete, wash three times with deionized water by centrifugation and dry to obtain 5,10,15,20-tetra(9-bromoanthryl)zincporphyrin (1-Zn) (188 mg, 90%).

[0081] 3) In a 10 ml reaction flask, add 5,10,15,20-tetratetra(9-bromoanthryl)zinc porphyrin (1-Zn) (170 mg, 0.12 mmol), 1,4-diethynylbenzene (30 mg, 0.24 mmol), bis(triphenylphosphine)palladium dichloride (34 mg, 0.048 mmol), and cuprous iodide (4.6 mg, 0.024 mmol). Transfer the reaction flask to a glove box and add dimethyl sulfoxide (DMSO, 2 ml). After complete dissolution, add triethylamine (1 ml) and stir at 100 °C for 30 min. After the reaction is complete, centrifuge with dichloromethane (DCM) to precipitate the product. After drying, immerse in trifluoroacetic acid to remove zinc, yielding polyporphyrin P-6 (128 mg, 85%).

[0082]

[0083] Example 8:

[0084] Polystyrene (M w Degradation of ~350,000 g / mol):

[0085] Polystyrene 1a (20.8 mg, 0.2 mmol (based on styrene monomer), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer)), and organic solvent (2.0 mL) with a weight average molecular weight of 350,000 g / mol were added to a test tube of a photoreactometer containing a magnetic field. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 16 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2, a white solid, was obtained by column chromatography.

[0086] The structure of the obtained compound 2 is as follows:

[0087]

[0088] The characterization results of the obtained compound 2 are as follows:

[0089] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0090] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0091] Table 2 shows the yield of benzoic acid produced by the degradation of polystyrene under different organic solvent conditions in Example 8 of this invention.

[0092]

[0093] Example 9:

[0094] Polystyrene (M w Degradation of ~350,000 g / mol):

[0095] Polystyrene 1a (weight average molecular weight 350,000 g / mol), P-1 (5 mol% (calculated as styrene monomer)), p-toluenesulfonic acid monohydrate (10 mol% (calculated as styrene monomer)), and ethyl acetate (2.0 mL) were added to a test tube containing a magnetic field in a photoreactometer. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 16 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2 was obtained as a white solid by column chromatography.

[0096] The structure of the obtained compound 2 is as follows:

[0097]

[0098] The characterization results of the obtained compound 2 are as follows:

[0099] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0100] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0101] Table 3 shows the yield of benzoic acid produced by the degradation of polystyrene under different concentrations of reaction solution containing styrene monomer in Example 9 of the present invention.

[0102]

[0103] Example 10:

[0104] Polystyrene (M w Degradation of ~350,000 g / mol):

[0105] Polystyrene 1a (20.8 mg, 0.2 mmol (based on styrene monomer), 0.1 M), P-1, p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer)), and ethyl acetate (2.0 mL) with a weight-average molecular weight of 350,000 g / mol were added to a test tube containing a magnetic field in a photoreactor. The test tube was placed in a WATTCAS photoreactor and stirred at room temperature under black LED illumination (365-370 nm, 20 W). After reacting for 16 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2, a white solid, was obtained by column chromatography.

[0106] The structure of the obtained compound 2 is as follows:

[0107]

[0108] The characterization results of the obtained compound 2 are as follows:

[0109] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0110] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0111] Table 4 shows the yield of polystyrene to benzoic acid under different photosensitizer P-1 dosages (calculated based on styrene monomer) in Example 10 of the present invention.

[0112]

[0113] Example 11:

[0114] Polystyrene (M w Degradation of ~350,000 g / mol):

[0115] Polystyrene 1a (20.8 mg, 0.2 mmol (based on styrene monomer), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer)), p-toluenesulfonic acid monohydrate, and ethyl acetate (2.0 mL) with a weight-average molecular weight of 350,000 g / mol were added to a test tube containing a magnetic field in a photoreactor. The test tube was placed in a WATTCAS photoreactor and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 16 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2 was obtained as a white solid by column chromatography.

[0116] The structure of the obtained compound 2 is as follows:

[0117]

[0118] The characterization results of the obtained compound 2 are as follows:

[0119] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0120] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0121] Table 5 shows the yield of benzoic acid generated from polystyrene under different amounts of p-toluenesulfonic acid monohydrate (calculated as styrene monomer) in Example 11 of the present invention.

[0122]

[0123] Example 12:

[0124] Polystyrene (M w Degradation of ~350,000 g / mol):

[0125] Polystyrene 1a (20.8 mg, 0.2 mmol (based on styrene monomer), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer)), additives (5 mol% (based on styrene monomer)), and ethyl acetate (2.0 mL) with a weight-average molecular weight of 350,000 g / mol were added to a test tube containing a magnetic field in a photoreactor. The test tube was placed in a WATTCAS photoreactor and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 16 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2, a white solid, was obtained by column chromatography.

[0126] The structure of the obtained compound 2 is as follows:

[0127]

[0128] The characterization results of the obtained compound 2 are as follows:

[0129] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0130] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0131] Table 6 shows the yield of benzoic acid generated from polystyrene under different additive conditions in Example 12 of this invention.

[0132]

[0133] Example 13:

[0134] Polystyrene (M w Degradation of ~350,000 g / mol):

[0135] Polystyrene 1a (20.8 mg, 0.2 mmol (based on styrene monomer), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer)), and ethyl acetate (2.0 mL) with a weight average molecular weight of 350,000 g / mol were added to a test tube of a photoreactometer containing a magnetic field. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for a period of time, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2, a white solid, was obtained by column chromatography.

[0136] The structure of the obtained compound 2 is as follows:

[0137]

[0138] The characterization results of the obtained compound 2 are as follows:

[0139] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0140] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0141] Table 7 shows the yield of benzoic acid generated from polystyrene degradation at different reaction times in Example 13 of this invention.

[0142]

[0143] Example 14:

[0144] Polystyrene (M w Degradation of ~350,000 g / mol):

[0145] Polystyrene 1a (20.8 mg, 0.2 mmol (based on styrene monomer), 0.1 M) with a weight-average molecular weight of 350,000 g / mol, insoluble polyporphyrin-based photosensitizer (5 mol% (based on styrene monomer)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer)), and ethyl acetate (2.0 mL) were added to a photoreactometer tube containing a magnetic field. The photoreactometer tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 48 hours, the residual insoluble polyporphyrin was removed by filtration, the product was dried by rotary evaporation, and then separated by column chromatography to obtain white solid benzoic acid 2.

[0146] The structure of the obtained compound 2 is as follows:

[0147]

[0148] The characterization results of the obtained compound 2 are as follows:

[0149] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0150] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0151] Table 8 shows the yield of polystyrene to benzoic acid under different insoluble polyporphyrin-based photosensitizer conditions in Example 14 of this invention.

[0152]

[0153]

[0154] Example 15:

[0155] Degradation of polystyrene:

[0156] Polystyrene 1 (20.8 mg, 0.2 mmol (calculated as styrene monomer), 0.1 M), P-1 (8.6 mg, 5 mol% (calculated as styrene monomer)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (calculated as styrene monomer)), and ethyl acetate (2.0 mL) were added to a test tube containing a magnetic field in a photoreactometer. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 48 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2 was obtained as a white solid by column chromatography.

[0157] The structure of the obtained compound 2 is as follows:

[0158]

[0159] The characterization results of the obtained compound 2 are as follows:

[0160] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0161] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0162] Table 9 shows the yields of benzoic acid generated from the degradation of polystyrene with different weight-average molecular weights in Example 15 of this invention.

[0163]

[0164] Example 16:

[0165] Styrene-butadiene copolymer (M w Degradation of styrene (~140,000 g / mol, 30 wt%):

[0166] A styrene-butadiene copolymer 1b (69.3 mg, 0.2 mmol (based on styrene monomer), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer)), and ethyl acetate (2.0 mL) with a styrene-toluene monomer content of 30% by mass and a weight average molecular weight of 140,000 g / mol were added to a test tube of a photoreactometer containing a magnetic field. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 48 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, the product was separated by column chromatography to obtain white solid benzoic acid 2 (12.3 mg, 50% yield).

[0167] The structure of the obtained compound 2 is as follows:

[0168]

[0169] The characterization results of the obtained compound 2 are as follows:

[0170] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0171] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0172] Example 17:

[0173] Styrene-acrylonitrile copolymer (M w Degradation of styrene (~165000 g / mol, 75 wt%):

[0174] A styrene-acrylonitrile copolymer 1c (27.7 mg, 0.2 mmol (based on styrene monomer), 0.1 M) containing 75% styrene (weight average molecular weight 165000 g / mol), P-1 (8.6 mg, 5 mol% (based on styrene monomer)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer)), and ethyl acetate (2.0 mL) with a magnetic flux were added to a test tube of a photoreactometer containing a magnetic flux. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 48 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, the product was separated by column chromatography to obtain white solid benzoic acid 2 (10.3 mg, yield 42%).

[0175] The structure of the obtained compound 2 is as follows:

[0176]

[0177] The characterization results of the obtained compound 2 are as follows:

[0178] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0179] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0180] Example 18:

[0181] Styrene-butadiene-acrylonitrile copolymer (M w Degradation of styrene (~238000 g / mol, 72 wt%):

[0182] A styrene-butadiene-acrylonitrile copolymer 1d (28.8 mg, 0.2 mmol (based on styrene monomer content), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer content)), p-toluenesulfonic acid monohydrate (3.8 mg, 10 mol% (based on styrene monomer content)), and ethyl acetate (2.0 mL) with a styrene-toluene-butadiene-acrylonitrile content of 72% by mass (weight average molecular weight 238000 g / mol), containing 72% styrene by mass, was added to a test tube of a photoreactometer containing a magnetic field. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED illumination (365-370 nm, 20 W). After reacting for 48 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, the product was separated by column chromatography to obtain white solid benzoic acid 2 (7.6 mg, yield 31%).

[0183] The structure of the obtained compound 2 is as follows:

[0184]

[0185] The characterization results of the obtained compound 2 are as follows:

[0186] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0187] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0188] Example 19:

[0189] Styrene-butadiene-acrylonitrile copolymer (M w Degradation of styrene (~238000 g / mol, 72 wt%):

[0190] A styrene-butadiene-acrylonitrile copolymer 1d (28.8 mg, 0.2 mmol (based on styrene monomer content), 0.1 M), P-1 (8.6 mg, 5 mol% (based on styrene monomer content)), trifluoroacetic acid (2.3 mg, 1.5 μL, 10 mol% (based on styrene monomer content)), and acetone (2.0 mL), containing 72% styrene by mass fraction and a weight average molecular weight of 238,000 g / mol, was added to a test tube containing a magnetic field in a photoreactometer. The test tube was placed in a WATTCAS photoreactometer and stirred at room temperature under black LED (365-370 nm, 20 W) illumination. After reacting for 48 hours, residual insoluble polyporphyrin was removed by filtration, and the product was dried by rotary evaporation. Then, benzoic acid 2 (9.8 mg, 40% yield) was obtained by column chromatography.

[0191] The structure of the obtained compound 2 is as follows:

[0192]

[0193] The characterization results of the obtained compound 2 are as follows:

[0194] 1 H NMR (400MHz, CDCl3) δ11.72(b,1H),8.14(d,J=6.8Hz,2H),7.63(t,J=7.4Hz,1H),7.49(t,J=7.8Hz,2H).

[0195] Compound 2 is a known compound, and its spectrum is completely consistent with the literature report (J.Am.Chem.Soc.2022,144,6532-6542).

[0196] In summary, this invention uses polymers containing styrene structural units of varying weight-average molecular weights as raw materials, insoluble polyporphyrin as a photosensitizer, and acid as an additive. The reaction is carried out under black light (wavelength range 365-370 nm) irradiation in an air atmosphere at room temperature in an organic solution, ultimately yielding benzoic acid. The reaction conditions are mild, the product yield is good, and the substrate range is broad. The insoluble polyporphyrin photosensitizer exhibits excellent photocatalytic activity, generating singlet oxygen in organic solvents and inducing benzyl radicals in styrene structural units. These radicals, under the influence of oxygen in the air, initiate the degradation of polymers containing styrene structural units, providing a green pathway for the photocatalytic degradation of polymers containing styrene structural units.

[0197] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0198] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for photocatalytic oxidative degradation of polymers containing styrene structural units, characterized in that, The steps are as follows: In a solvent and an insoluble polyporphyrin-based photosensitizer, with acid as an additive, under black light irradiation conditions of 365-370 nm wavelength and 20 W power, polymers containing styrene structural units are oxidized and degraded by air to produce benzoic acid. The general reaction formula is as follows: ； Wherein, 1 is a polymer containing styrene structural units, where x cannot be 0, but y and z can be 0; 2 is benzoic acid; The additive is one of sulfuric acid, hydrochloric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid monohydrate, zinc chloride, ytterbium trifluoromethanesulfonate, and scandium trifluoromethanesulfonate, and is used in an amount of 2.5-50 mol% of the styrene monomer in the polymer containing styrene structural units. There are seven different structures of insoluble polyporphyrin-based photosensitizers. Among them, P-1 is prepared by polymerization of 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:

2. Its structural formula is as follows: ； P-2 is prepared by polymerization of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:

2. Its structural formula is as follows: ； P-3 was synthesized by polymerization of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin and 1,7-octadiyne in a molar ratio of 1:

2. Its structural formula is as follows: ； P-4 is obtained by self-polymerization of 4,4'-[10,20-bis(4-bromophenyl)-5,15-bis(2-ethynylphenyl)]porphyrin, and its structural formula is as follows: ； P-5 is synthesized by polymerization of 5,10,15,20-tetratetrafluorophenyl (4-bromo-2,3,5,6-tetrafluorophenyl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:

2. Its structural formula is as follows: ； P-6 was synthesized by polymerization of 5,10,15,20-tetrakis(4-bromo-3,5-dimethoxyphenyl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:

2. Its structural formula is as follows: ； P-7 is synthesized by polymerization of 5,10,15,20-tetrakis(9-bromoanthryl)porphyrin and 1,4-diethynylbenzene in a molar ratio of 1:

2. Its structural formula is as follows: ； The reaction temperature is room temperature, and the reaction time is 16-72 hours.

2. The photocatalytic oxidative degradation method for polymers containing styrene structural units according to claim 1, characterized in that, The concentration of styrene monomer in the polymer reaction solution containing styrene structural units is 0.05-0.5 M.

3. The photocatalytic oxidative degradation method for polymers containing styrene structural units according to claim 1, characterized in that, The amount of the insoluble polyporphyrin-based photosensitizer is 1-10 mol of styrene monomer in the polymer containing styrene structural units.

4. The photocatalytic oxidative degradation method for polymers containing styrene structural units according to claim 1, characterized in that, The solvent is one of 1,2-dichloroethane, acetone, dimethyl carbonate, and ethyl acetate.

5. The photocatalytic oxidative degradation method for polymers containing styrene structural units according to claim 1, characterized in that, It also includes a post-processing procedure, which involves filtering to remove residual insoluble polyporphyrin photosensitizer, rotary evaporation for drying, separation by column chromatography, and drying the product in a vacuum drying oven to constant weight.

6. The photocatalytic oxidative degradation method for polymers containing styrene structural units according to claim 1, characterized in that, Polymers containing styrene structural units include different polystyrene with a weight average molecular weight of 65,000-650,000 g / mol, a styrene-butadiene copolymer with a weight average molecular weight of 140,000 g / mol and a styrene mass fraction of 30%, a styrene-acrylonitrile copolymer with a weight average molecular weight of 165,000 g / mol and a styrene mass fraction of 75%, and a styrene-butadiene-acrylonitrile copolymer with a weight average molecular weight of 238,000 g / mol and a styrene mass fraction of 72%.

7. The photocatalytic oxidative degradation method for polymers containing styrene structural units according to claim 1, characterized in that, The preparation method of insoluble polyporphyrin-based photosensitizer P-1 is as follows: 7,8,17,18-tetrahydro-5,10,15,20-tetra(4-bromophenyl)-21H,23H-zinc porphyrin and 1,4-diethynylbenzene were added to a reaction flask in a molar ratio of 1:2, along with bis(triphenylphosphine)palladium dichloride and cuprous iodide. The reaction flask was then transferred to a glove box, where dimethyl sulfoxide was added as a solvent. After complete dissolution, triethylamine was added, and the mixture was stirred at 100°C for 30 min. After the reaction was completed, the product was centrifuged with dichloromethane to precipitate it. After drying, the product was soaked in trifluoroacetic acid to remove zinc, yielding the insoluble polyporphyrin-based photosensitizer P-1.

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