Method for oriented high-valuing of polycarbonate under action of polyion liquid catalyst

Abstract

The invention discloses a method for directionally increasing the value of polycarbonate under the action of a polyion liquid catalyst, and belongs to the technical field of depolymerization and recovery of high polymer materials. Adding a cross-linking agent and an initiator, carrying out a heating copolymerization reaction in an organic solvent system in an inert gas atmosphere, and carrying out post-treatment, a reaction system comprising polycarbonate, the polyion liquid catalyst, an epoxy compound and a polar solvent is further constructed, and the reaction system is placed at the temperature of 130-150 DEG C in an air atmosphere for a reaction for more than or equal to 6 h, so that oriented high-valued conversion of polycarbonate into bisphenol A and cyclic carbonate can be realized; the method has a wide application prospect in the field of waste plastic treatment.

Description

Technical Field

[0001] The invention relates to the technical field of depolymerization and recovery of polymer materials, and in particular to a method for directional high-value conversion of polycarbonate under the action of a polyionic liquid catalyst. Background Art

[0002] Ionic liquids are organic salts composed of anions and cations. They are in liquid form and have the advantages of being non-volatile, non-flammable, highly conductive, and having good thermal stability. They are now widely used in catalysis, separation, organic synthesis, medical materials, and other fields. Polyionic liquids are derived from ionic liquid monomers. The cations or anions or both of the ionic liquid monomers are incorporated into the polymer skeleton. Compared with ionic liquids, the ionic part of polyionic liquids has adjustable space, better processability, designability, and recyclability. A variety of polyionic liquids have been developed. For example, Chinese patent document with publication number CN116574214A discloses a polyionic liquid catalyst and its preparation method and application. The invention uses 1-vinyl-3-butyl imidazolium hydrogen sulfate monomer and hydrogen sulfate crosslinking agent under the action of an initiator to carry out a polymerization reaction to obtain a polyionic liquid catalyst combining the advantages of solid acid, ionic liquid and polymer for the esterification reaction of acid and alcohol; Chinese patent document with publication number CN108689838A discloses a swellable acidic polyionic liquid. The polyionic liquid uses 1-vinyl-3-alkyl imidazolium bromide ionic liquid and sodium acrylate as comonomers, is obtained by free radical polymerization and acidification with an equimolar amount of acid, and can be used to catalyze the esterification of formic acid and olefins to prepare formic esters.

[0003] Plastic products provide great convenience for modern life. However, with the increasing use of plastics, it has become a top priority to improve the recycling rate of waste plastics. Traditional plastic recycling technology is difficult to fully utilize carbon resources and has problems with environmental safety and biosafety. Chemical recycling technology can convert waste plastics into basic chemical raw materials or other high-value-added chemicals to achieve resource appreciation. This technology of converting waste plastics into chemical monomers is of great significance to promoting the sustainable circular development of the plastic economy. At present, there are no reports on the use of polyionic liquids for the value-added conversion of waste plastics.

[0004] Polycarbonate (PC) plastic has excellent physical properties, chemical properties and processing properties. It is a non-crystalline thermoplastic plastic and occupies an important position in the engineering plastics market. Although some studies have reported that ionic liquid catalysts can be used for the depolymerization of polycarbonate (Chinese patent documents with publication numbers CN117603044A and CN101429100A, etc.), the ionic liquid catalyst is difficult to separate from the product, which increases the difficulty of subsequent purification steps and may also lead to product contamination and ionic liquid loss. Summary of the invention

[0005] In order to solve the deficiencies in the above-mentioned prior art, the present invention provides the use of polyionic liquid catalysts in depolymerization and recovery of polycarbonate, as well as a method for directional high-value polycarbonate under the action of corresponding polyionic liquid catalysts, which has broad application prospects in the field of waste plastics treatment.

[0006] The specific technical solutions adopted are as follows: Application of polyionic liquid catalyst in depolymerization and recovery of polycarbonate, the polyionic liquid catalyst is prepared by the following method: using ionic liquid and acrylate as comonomers, adding a crosslinking agent and an initiator, heating copolymerization reaction in an organic solvent system under an inert gas atmosphere, and obtaining the polyionic liquid catalyst through post-treatment; The ionic liquid is selected from 1-vinyl-3-ethylimidazolium bromide ([VEIm][Br]), 1-vinyl-3-butylimidazolium bromide ([VBIm][Br]), 1-vinyl-3-ethylimidazolium tetrafluoroborate ([VEIm][BF 4 ])、1-vinyl-3-ethylimidazolium hexafluorophosphate([VEIm][PF 6 ]); The molar ratio of the ionic liquid to the acrylate is 0.5-2:1; The temperature of the heated copolymerization reaction is 60-110°C and the time is 8-24 h.

[0007] Specifically, the polycarbonate is bisphenol A polycarbonate; and the acrylate is selected from zinc acrylate, sodium acrylate or magnesium acrylate.

[0008] The initiator includes azobisisobutyronitrile, and the crosslinking agent includes divinylbenzene.

[0009] Further preferably, the amount of the initiator added is 20-50wt% of the total mass of the comonomers, and the amount of the crosslinking agent added is 20-60wt% of the total mass of the comonomers.

[0010] Preferably, the organic solvent comprises acetonitrile, methanol or ethanol.

[0011] Preferably, the inert gas atmosphere is a nitrogen atmosphere, and the post-treatment method is: cooling the reaction solution, further filtering it, washing it with water and ethanol, and vacuum drying it to obtain the polyionic liquid catalyst.

[0012] The present invention also provides a method for directional high-value polycarbonate under the action of a polyionic liquid catalyst, the method comprising: A reaction system comprising polycarbonate, the polyionic liquid catalyst, an epoxy compound and a polar solvent is constructed, and the reaction system is placed at a temperature of 130 to 150° C. in an air atmosphere for a reaction of ≥6 h to obtain bisphenol A and a cyclic carbonate; The polar solvent is selected from N -Methylpyrrolidone, N , N - dimethylformamide, or N -Methylpyrrolidone, N , N - a mixture of at least one of dimethylformamide and water. The polar solvent significantly enhances the contact efficiency between the polyionic liquid catalyst and the polymer substrate by promoting the swelling and dissolution of the polycarbonate.

[0013] The epoxy compound is at least one of styrene oxide, 1,2-propylene oxide or 1,2-butylene oxide.

[0014] Preferably, the molar ratio of polycarbonate to epoxy compound is 1:0.5-3; and the amount of polyionic liquid catalyst added is 1-30 wt % of the mass of polycarbonate.

[0015] Further preferably, the molar ratio of polycarbonate to epoxy compound is 1:1-2; based on 100% molar number of polycarbonate, the amount of polyionic liquid catalyst added is 15-30wt%. Under the above raw material ratio, it is beneficial to promote the full depolymerization of polycarbonate and the efficient generation of bisphenol A and cyclic carbonate, and avoid unnecessary increase in raw material cost, while taking into account the reaction efficiency and economy.

[0016] Preferably, the ratio of polycarbonate to polar solvent is 1 g:5-15 mL.

[0017] Further preferably, the polar solvent is selected from N -Methylpyrrolidone, N , N - A mixture of at least one organic solvent and water in dimethylformamide, wherein the volume ratio of water to organic solvent is 0.3-2: 100. The organic solvent promotes the swelling of the polymer, and water acts as a nucleophilic agent to attack PC and hydrolyze it.

[0018] Further preferably, in order to take into account both reaction efficiency and product yield, the reaction system is placed at a temperature of 130 to 150° C. under air atmosphere for reaction for 6 to 10 hours.

[0019] The present invention also provides the application of the method for directional high-value conversion of polycarbonate under the action of polyionic liquid catalyst in the treatment of waste plastics.

[0020] Specifically, the waste plastic is waste made of bisphenol A polycarbonate, including waste CDs, waste buckets, waste films, waste bottles, waste plates, waste sheets, etc. The method of the present invention is applicable to various forms of waste polycarbonate samples.

[0021] When upgrading and converting waste plastics, they need to be crushed into centimeter-sized flakes, particles or powders in advance to ensure their resource utilization effect, so as to obtain bisphenol A and cyclic carbonates in a targeted manner with high yield.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides an efficient dual upgrading and conversion method of bisphenol A polycarbonate, which realizes the selective cleavage and reconstruction of carbonate bonds and bisphenol A units in polycarbonate molecules.

[0023] (2) The method for directional high-value-added polycarbonate under the action of polyionic liquid catalyst in the present invention has a wide range of substrate applicability, not only limited to styrene oxide, but also applicable to 1,2-propylene oxide and 1,2-butylene oxide. The reaction conditions are mild, and it has higher environmental friendliness, resource utilization efficiency and operational safety, high chemical monomer yield and high application value.

[0024] (3) The polyionic liquid catalyst used in the present invention has good mechanical strength and chemical stability. After the reaction is completed, the catalyst can be quickly recovered by simple centrifugal separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FT-IR spectra of polyionic liquid VB-Br-Zn-MeCN and ionic liquid monomer [VBIm][Br].

[0026] Figure 2 The reaction scheme equation in the representative embodiment 1 is shown in FIG. DETAILED DESCRIPTION

[0027] The present invention will be further illustrated below in conjunction with the examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples that do not specify specific conditions are usually performed under normal conditions or according to the conditions recommended by the manufacturer. The content that is not described in detail in this specification sheet belongs to the prior art known to professionals in the field. The experimental materials used in the following examples, if not otherwise specified, can be purchased by conventional biochemical reagent companies.

[0028] In a 25 mL Schlenk tube, 1-vinyl-3-butylimidazolium bromide [VBIm][Br] (2 mmol), zinc acrylate (1 mmol), 2,2'-azobisisobutyronitrile (AIBN, 1.1 mmol, as a free radical initiator), divinylbenzene (DVB, 2 mmol, as a crosslinker) and acetonitrile (6 mL, as a reaction solvent) were added in sequence. The reaction mixture was placed in a 70 °C oil bath and polymerized for 12 hours under an inert atmosphere. After the reaction was completed, the system was cooled to room temperature, the product was separated by filtration, and washed with distilled water and ethanol three times each to remove unreacted monomers and impurities. Finally, the crude product was vacuum dried at 60 °C for 12 hours to obtain the target product VB-Br-Zn-MeCN.

[0029] Under the same conditions, replace [VBIm][Br] with [VEIm][Br], [VEIm][BF 4 ] or [VEIm][PF 6 ], and VE-Br-Zn-MeCN and VE-BF were obtained respectively. 4 -Zn-MeCN, VE-PF 6 -Zn-MeCN.

[0030] Under the same conditions, zinc acrylate is replaced by magnesium acrylate or sodium acrylate to obtain VB-Br-Mg-MeCN or VB-Br-Na-MeCN.

[0031] Under the same conditions, acetonitrile was replaced by methanol or ethanol to obtain VB-Br-Zn-MeOH or VB-Br-Zn-EtOH.

[0032] The FT-IR spectra of VB-Br-Zn-MeCN and [VBIm][Br] are shown in Figure 1 As shown in Figure 2, infrared spectroscopy confirmed the presence of IL monomers in the polyionic liquid: 2885~3006 cm - ¹ is the CH stretching vibration of the imidazole ring, 1445 and 1390 cm - ¹ is the vibration of imidazole ring skeleton, 1152 cm - ¹ is the stretching vibration of the imidazole ring. Compared with pure [VBIm][Br], 1654 cm - The disappearance of the C=C stretching vibration peak at ¹ further supports this conclusion. - The C=O stretching vibration at ¹ and 660 cm - The Zn-O stretching vibration at ¹ indicates that zinc acrylate is involved in the polymerization reaction.

[0033] The reaction processes of the following examples and comparative examples were all carried out under normal pressure without applying additional pressure. The polycarbonate PC powders used were all bisphenol A polycarbonate. The reaction scheme is shown in FIG. Figure 2 shown.

[0034] Example 1 PC powder (0.508 g, 2 mmol), styrene oxide (SO, 3 mmol), and polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to the mass of PC) were added in sequence in a 10 mL Schlenk tube. N -Methyl pyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction product to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yield of bisphenol A in this example was 71%, and the yield of styrene carbonate was 77%.

[0035] Example 2 PC powder (0.508 g, 2 mmol), styrene oxide (SO, 3 mmol), and different polyionic liquid catalysts (VE-Br-Zn-MeCN, VE-BF 4 -Zn-MeCN, VE-PF 6 -Zn-MeCN, 20 wt%, relative to PC mass), and N -Methyl pyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this example were 63%, 52% and 56%, respectively, and the yields of styrene carbonate were 47%, 17% and 0%, respectively.

[0036] Example 3 PC powder (0.508 g, 2 mmol), styrene oxide (SO, 3 mmol), and polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to the mass of PC) were added to multiple 10 mL Schlenk tubes.N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methylpyrrolidone 0.36%, 0.54%, 0.72%, 0.9%) and N -Methyl pyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 74%, 83%, 99% and 99%, respectively, and the yields of styrene carbonate were 80%, 86%, 98% and 99%, respectively.

[0037] The amount of deionized water added is N -methyl pyrrolidone 0.72% experimental parameters, after the reaction is completed, the polyionic liquid catalyst is centrifuged and separated, and the separated polyionic liquid catalyst is transferred to a 10 mL Schlenk tube, and no additional polyionic liquid catalyst is added. The other reaction conditions and parameters are the same. After four repeated cycles, the yield of bisphenol A is 99%, and the yield of styrene carbonate is 94%.

[0038] Example 4 PC powder (2 mmol), different moles of styrene oxide (the molar ratio of PC powder to styrene oxide was 1:1.3, 1:1.8, and 1:2, respectively), and polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to the mass of PC) were added to multiple 10 mL Schlenk tubes. N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methyl pyrrolidone (0.72%, 0.036 g) and N-methyl pyrrolidone (NMP, 5 mL) were used as reaction solvents. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as an internal standard and the results were analyzed by nuclear magnetic resonance spectroscopy ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 94%, 99%, and 99%, respectively, and the yields of styrene carbonate were 95%, 99%, and 99%, respectively.

[0039] Example 5 PC powder (2 mmol), styrene oxide (SO, 3 mmol), and different masses of polyionic liquid catalyst VB-Br-Zn-MeCN (15 wt %, 30 wt %, relative to the mass of PC) were added to multiple 10 mL Schlenk tubes, and deionized water ( N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methylpyrrolidone 0.72%, 0.036 g) and N -Methyl pyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 95% and 99%, and the yields of styrene carbonate were 92% and 99%, respectively.

[0040] Example 6 PC powder (2 mmol), styrene oxide (SO, 3 mmol), polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to PC mass), and deionized water (20 wt%) were added to a 10 mL Schlenk tube. N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methylpyrrolidone 0.72%, 0.036 g) and N -Methylpyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 130 and 150 °C under air atmosphere, and the reaction was carried out for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard, and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 93% and 99%, respectively, and the yields of styrene carbonate were 81% and 99%, respectively.

[0041] Example 7 In several 10 mL Schlenk tubes, 0.254 g cm-scale PC waste crushed materials (buckets, CDs, transparent plates, about 2 mmol), styrene oxide (SO, 3 mmol), polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to the mass of PC), and deionized water (about 100 mL) were added. N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methylpyrrolidone 0.72%, 0.036 g) and N -Methyl pyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 95%, 97%, and 98%, respectively, and the yields of styrene carbonate were 94%, 96%, and 95%, respectively.

[0042] Example 8 PC powder (2 mmol), different epoxy compounds (1,2-propylene oxide, 1,2-butylene oxide, 3 mmol), and polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to the mass of PC) were added to multiple 10 mL Schlenk tubes, and deionized water (100 mL) was used to separate the two. N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methylpyrrolidone 0.72%, 0.036 g) and N -Methyl pyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 10 hours under continuous stirring. After the reaction was completed, the reaction mixture was quickly transferred to an ice water bath and cooled to room temperature. Trioxane was used as the internal standard and the NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 98% and 96%, respectively, and the yields of cyclic carbonate were 97% and 98%, respectively. The corresponding structural formula of cyclic carbonate is shown below: .

[0043] Example 9 PC powder (2 mmol), styrene oxide (SO, 3 mmol), and polyionic liquid catalyst VB-Br-Zn-MeCN (20 wt%, relative to the mass of PC) were added to several 10 mL Schlenk tubes, and deionized water ( N -Methyl pyrrolidone is taken as 1, and the amount of deionized water added is N -methylpyrrolidone 0.72%, 0.036 g) and N -Methylpyrrolidone (NMP, 5 mL) was used as the reaction solvent. The reaction system was placed in an oil bath preheated to 140 °C under air atmosphere and reacted for 8 h, 9 h, 11 h and 12 h respectively under continuous stirring. After the reaction, the reaction mixture was quickly transferred to an ice-water bath and cooled to room temperature. Trioxane was used as the internal standard and the results were analyzed by H NMR ( 1 H NMR) was used to quantitatively analyze the reaction products to determine the yields of bisphenol A and cyclic carbonate. The results showed that the yields of bisphenol A in this embodiment were 85%, 92%, 99%, and 99%, respectively, and the yields of styrene carbonate were 83%, 87%, 99%, and 99%, respectively.

[0044] Comparative Example 1 The method for directional high-value polycarbonate under the action of polyionic liquid catalyst in this comparative example and Example 3 (the amount of deionized water added is N -methylpyrrolidone 0.72%) is that no polyionic liquid catalyst and deionized water are added, and the other reaction conditions and parameters are the same. After the reaction is completed, a mixed solution is obtained. The obtained mixed solution is passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yield of bisphenol A in this comparative example was 18.3%, and the yield of styrene carbonate was 7.4%.

[0045] Comparative Example 2 The method for directional high-value polycarbonate under the action of polyionic liquid catalyst in this comparative example and Example 3 (the amount of deionized water added is N -methylpyrrolidone), without adding polyionic liquid catalyst and deionized water, adding 20 wt% [VBIm] [Br], the other reaction conditions and parameters are the same, after the reaction is completed, a mixed solution is obtained, and the obtained mixed solution is passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yield of bisphenol A in this comparative example was 32.7%, and the yield of styrene carbonate was 10%.

[0046] Comparative Example 3 The method for directional high-value polycarbonate under the action of polyionic liquid catalyst in this comparative example and Example 3 (the amount of deionized water added isN -0.72% of methylpyrrolidone), without adding NMP, adding 5mL of water, and the other reaction conditions and parameters are the same. After the reaction is completed, a mixed solution is obtained, and the obtained mixed solution is passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yield of bisphenol A in this comparative example was 0%, and the yield of styrene carbonate was 0%.

[0047] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of polyionic liquid catalyst in depolymerization and recovery of polycarbonate, characterized in that: The polyionic liquid catalyst is prepared by the following method: using ionic liquid and acrylate as comonomers, adding a crosslinking agent and an initiator, heating copolymerization in an organic solvent system under an inert gas atmosphere, and obtaining the polyionic liquid catalyst through post-treatment; The ionic liquid is selected from at least one of 1-vinyl-3-ethylimidazolium bromide, 1-vinyl-3-butylimidazolium bromide, 1-vinyl-3-ethylimidazolium tetrafluoroborate, and 1-vinyl-3-ethylimidazolium hexafluorophosphate; The molar ratio of the ionic liquid to the acrylate is 0.5-2:1; The temperature of the heated copolymerization reaction is 60-110°C and the time is 8-24 h.

2. The use of the polyionic liquid catalyst according to claim 1 in depolymerization and recovery of polycarbonate, characterized in that: The acrylate salt is selected from zinc acrylate, sodium acrylate or magnesium acrylate.

3. The use of the polyionic liquid catalyst according to claim 1 in depolymerization and recovery of polycarbonate, characterized in that: The initiator includes azobisisobutyronitrile and the crosslinking agent includes divinylbenzene.

4. A method for directional high-value polycarbonate under the action of a polyionic liquid catalyst, characterized in that: Methods include: A reaction system including polycarbonate, a polyionic liquid catalyst, an epoxy compound and a polar solvent is constructed, and the reaction system is placed at a temperature of 130 to 150° C. in an air atmosphere for a reaction of 6 hours or more to obtain bisphenol A and a cyclic carbonate; The polar solvent is selected from N -Methylpyrrolidone, N , N - dimethylformamide, or N -Methylpyrrolidone, N , N - a mixture of at least one of dimethylformamide and water.

5. The method for directional high-value polycarbonate under the action of a polyionic liquid catalyst according to claim 4, characterized in that: The epoxy compound is at least one of styrene oxide, 1,2-propylene oxide or 1,2-butylene oxide.

6. The method for directional high-value polycarbonate under the action of a polyionic liquid catalyst according to claim 4, characterized in that: The molar ratio of polycarbonate to epoxy compound is 1:0.5-3; the added amount of polyionic liquid catalyst is 1-30wt% of the mass of polycarbonate.

7. The method for directional high value of polycarbonate under the action of a polyionic liquid catalyst according to claim 4, characterized in that: The ratio of polycarbonate to polar solvent is 1 g:5-15 mL.

8. The method for directional high-value polycarbonate under the action of a polyionic liquid catalyst according to claim 4, characterized in that: The polar solvent is selected from N -Methylpyrrolidone, N , N - A mixture of at least one organic solvent and water in dimethylformamide.

9. The method for directional high value of polycarbonate under the action of a polyionic liquid catalyst according to claim 4, characterized in that: The reaction system is placed at 130-150° C. under air atmosphere for 6 h-12 h.

10. Use of the method for directional high-value conversion of polycarbonate under the action of a polyionic liquid catalyst according to any one of claims 4 to 9 in the treatment of waste plastics.

Images