Application of a catalyst in the reaction for catalytic synthesis of bio-based polycarbonate

Abstract

The present invention relates to the application of a catalyst in the reaction of catalytic synthesis of bio-based polycarbonate. In the present invention, isosorbide is used to replace bisphenol A to prepare bio-based polycarbonate with organic carbonate. On the one hand, renewable biomass raw materials are utilized, realizing the green chemistry concept of sustainable development. On the other hand, the toxicity problem of bisphenol A polycarbonate in the field of plastic products for many years is also solved. The method for preparing the bio-based polycarbonate in the present invention is simple and easy to operate. The raw materials are derived from biomass and have a high utilization rate. The obtained bio-based polycarbonate is a brown solid and non-toxic. Its thermal properties are similar to those of bisphenol A polycarbonate, and the weight-average molecular weight can reach 5×10<supgt;5< / supgt>.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to the application of a catalyst in the reaction of catalytic synthesis of bio-based polycarbonate, specifically the application of synthesizing bio-based polycarbonate by catalyzing the transesterification reaction of diphenyl carbonate and bio-based monomer isosorbide. Background Art

[0002] Bio-based plastics based on bio-based chemicals are ideal green polymer materials due to their good biocompatibility, excellent processing performance and mechanical properties, and have attracted extensive attention from the academic community and governments of various countries. Therefore, developing a plastic synthesis process route based on bio-based chemicals is an important way to alleviate the greenhouse effect and realize the high-value utilization of resources, and has important research significance for assisting the green transformation and sustainable development of the chemical industry, and promoting carbon peak and carbon neutrality.

[0003] Bio-based plastics refer to new materials whose production raw materials are all or partially derived from biomass (such as succinic acid, bio-based 1,4-butanediol, bio-based 1,3-propanediol, bio-based ethylene glycol, CO2, etc.), and have excellent emission reduction capabilities. At present, the production of polycarbonate still mainly uses bisphenol A type polycarbonate. The reaction raw materials of this type have high toxicity and are not suitable for regeneration. Therefore, it has good economic and social value to use isosorbide to replace bisphenol A of petroleum-based raw materials and adopt the melt transesterification method instead of the phosgene method in the process to produce polycarbonate. However, the catalysts for this process route have problems such as low catalytic activity, low conversion rate and yield, and low product polymerization degree. Therefore, it is urgent to develop a catalyst with excellent catalytic performance. In summary, the research results illustrate that developing a catalyst with excellent performance to catalyze bio-based raw materials or their chemicals to prepare bio-based polycarbonate has good application prospects and alleviates the environmental pollution problems existing in traditional plastics to a certain extent. Summary of the Invention

[0004] Object of the Invention:

[0005] The present invention provides the application of a catalyst in the reaction of catalytic synthesis of bio-based polycarbonate, and the application of synthesizing bio-based polycarbonate by catalyzing the transesterification and polycondensation reaction of diphenyl carbonate and isosorbide with a metal cation-anion coordination type ionic liquid catalyst. The present invention not only utilizes the renewable bio-based isosorbide to replace bisphenol A, realizing the green chemical concept of sustainable development, but also solves the toxicity problem of bisphenol A type polycarbonate in the application field of plastic products for many years, develops a new catalyst and technical route for the preparation of bio-based polycarbonate, and effectively solves the problems such as poor conversion rate and stability existing in traditional catalysts.

[0006] Technical Solution:

[0007] Application of a catalyst in the synthesis of bio-based polycarbonate by transesterification and polycondensation of isosorbide and diphenyl carbonate;

[0008] The catalyst is a metal cation-anion coordination ionic liquid catalyst with the following structure:

[0009]

[0010] Me = Zn, Cu, Mg, Fe, Al.

[0011] Furthermore, the application method is as follows:

[0012] Under atmospheric pressure, isosorbide, diphenyl carbonate and the catalyst are mixed and put into a reaction kettle. The molar ratio of diphenyl carbonate to isosorbide is 1 - 1.1:1. It is heated to 150 °C and maintained at this temperature for 0.5 h; then, the reaction temperature is raised from 150 °C to 165 - 185 °C, and the pressure is reduced to 2 - 6 kPa, and the transesterification reaction is continued for 20 - 60 min to remove the by-product phenol by vacuum distillation; thereafter, the temperature is gradually raised to 210 - 250 °C, and the pressure is reduced to 5 kPa - 100 Pa, and the polycondensation reaction is continued for 0.5 - 4 h. After the reaction is completed, the final product, bio-based polycarbonate, is obtained.

[0013] Furthermore, the catalyst dosage is 0.2 - 0.6% of the total mass of the reactants.

[0014] Preferably, the catalyst dosage is 0.4% of the total mass of the reactants.

[0015] Beneficial effects:

[0016] (1) In the present invention, bio-based isosorbide is used to replace bisphenol A as the raw material to synthesize polycarbonate, realizing the green chemistry concept of sustainable development and solving the toxicity problem of bisphenol A polycarbonate in the field of plastic products for many years.

[0017] (2) The method for preparing bio-based polycarbonate in the present invention is simple and easy to operate. The raw materials are derived from biomass and have a high utilization rate. The obtained bio-based polycarbonate is a brown solid and non-toxic. Its thermal properties are similar to those of bisphenol A polycarbonate, and the weight-average molecular weight can reach 5×10 5 .

[0018] (3) The polycarbonate synthesis route in the present invention is green and pollution-free, the process is simple, the atom utilization rate is high, and the small molecule by-product is water and harmless.

[0019] (4) The catalyst in the system of the present invention has stronger coordination and nucleophilic ability compared with traditional catalysts. The cation and anion have a synergistic effect, which can improve the reaction conversion rate, enhance the catalytic activity and reaction selectivity. Description of the Drawings

[0020] Figure 1 Schematic diagram for catalyst synthesis;

[0021] Figure 2 Infrared spectrum analysis diagram of the prepared catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3;

[0022] Figure 3 Thermogravimetric analysis diagram of the prepared catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3;

[0023] Figure 4 X-ray spectrum analysis diagram of the prepared catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3 and intermediate II (a intermediate II, b 1,3-(p-toluic acid Zinc Salt)Im ZnCl3);

[0024] Figure 5 Comparative infrared spectrum analysis diagram of the traditional catalyst zinc acetate and the polycarbonate synthesized in Examples 1-3 (where a is the product of zinc acetate, b is the product of Example 1, c is the product of Example 2, and d is the product of Example 3);

[0025] Figure 6 Thermogravimetric analysis diagram of the polycarbonate products of Example 1 and Example 7 (where PC is the product of Example 7 and PIC is the product of Example 1);

[0026] Figure 7 Differential scanning calorimetry analysis diagram of the polycarbonate products of Examples 1-3 and Example 7 (where PC is the product of Example 7, PIC-3 is the product of Example 1, PIC-2 is the product of Example 2, and PIC-1 is the product of Example 3);

[0027] Figure 8 Gel permeation chromatography analysis diagram of the polycarbonate product of Example 1.

[0028] Figure 9 1H NMR analysis diagram of the polycarbonate product of Example 1. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0030] The catalyst of the present invention is an ionic liquid catalytic system in which organic compounds such as imidazole and 4-(chloromethyl)benzoic acid cooperate with an inorganic metal nitrate compound zinc nitrate to form cations, and halogen chlorine and metal chloride form metal chloride anions to form anion-cation coordinated catalysis. The catalyst is stable in nature, easy to store, pollution-free, and has higher selectivity, reaction conversion rate and catalytic activity for ester exchange reaction.

[0031] The catalyst structure is as follows:

[0032]

[0033] Me=Zn, Cu, Mg, Fe, Al.

[0034] Our research group discovered that zinc acetate, due to its oxygen-zinc coordination chelation structure, exhibits excellent catalytic activity for transesterification and polycondensation reactions. Subsequently, during the study of ionic liquid catalysis, we discovered that imidazole organic compounds, among nitrogen-containing heterocyclic rings, exhibit excellent selectivity for transesterification reactions. The introduction of different metal chlorides into the anion can enhance the synergistic catalytic effect of anions and cations. This is due to the ability of the dihydrogen on the imidazole ring to form a hydrogen bond with the oxygen of the carbonyl carbon group on the carbonate, breaking the carbon-oxygen double bond and making the carbonyl carbon positively charged. Simultaneously, the free anion captures the hydrogen from the hydroxyl group and attacks the positively charged carbonyl carbon group, significantly improving the selectivity and conversion of the catalyst system compared to other catalyst types. Furthermore, the 4-chloromethyl group and imidazole can undergo graft halogenation reactions well, achieving high grafting efficiency even within the confined pores of the metal-organic framework. This also improves the thermal stability of the catalyst system without compromising the catalytic activity of the imidazole. Therefore, the present invention proposes to simultaneously introduce 4-(chloromethyl)benzoic acid on both sides of imidazole, and then coordinate and chelate with metal compounds to prepare metal anion and cation coordination ionic liquid catalysts, which can achieve synergistic catalysis and effectively improve catalytic activity and structural stability.

[0035] The metal anion and cation coordination ionic liquid catalysts prepared in the following examples are used to catalyze the reaction of diphenyl carbonate and isosorbide to synthesize bio-based polycarbonate.

[0036] Example 1

[0037] Preparation of Catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3

[0038] (1) Preparation of intermediate I

[0039] 0.1 mol of 4-(chloromethyl)benzoic acid and 0.05 mol of imidazole were added to a high-gravity reactor and reacted at 25°C in a solvent-free environment for 4 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain intermediate I with a yield of 85%.

[0040] (2) Preparation of Intermediate II

[0041] 0.1 mol of Intermediate I and 0.025 mol of zinc nitrate were added to a precision kettle, 30 mL of deionized water was added, and the mixture was heated in an oven at 80 °C for 20 h. After stopping heating, it was naturally cooled for 10 h. Then, it was subjected to suction filtration, stirring and washing, and vacuum drying to obtain Intermediate II with a yield of 73%.

[0042] (3) Preparation of the Target Catalyst

[0043] 0.03 mol of Intermediate II and 0.032 mol of zinc chloride were added to a molecular reactor, 50 mL of distilled water was added as a solvent, and the reaction was carried out under a vacuum at 50 °C for 10 h. After the reaction ended, it was subjected to suction filtration, washing and drying to obtain the target product with a yield of 98%.

[0044] The above-prepared metal cation-anion coordination ionic liquid catalyst was used to catalyze the reaction of diphenyl carbonate and isosorbide to synthesize bio-based polycarbonate. The catalytic experimental conditions were as follows: the molar ratio of diphenyl carbonate to isosorbide was 1.06:1, the catalyst dosage was 0.4% of the total mass of the reactants, nitrogen was introduced and purged for 1 - 2 min to remove the air in the reaction device, and then it was heated to 150 °C and maintained at this temperature for 0.5 h. Then, the reaction temperature was raised from 150 °C to 175 °C, and the pressure was reduced to 4 kPa, and the transesterification reaction was carried out for 40 min to remove the by-product phenol by vacuum distillation. Thereafter, the temperature was gradually raised to 240 °C, the pressure dropped to 500 Pa, and the polycondensation reaction was carried out for 1 h. After the reaction ended, the obtained product was dissolved in dichloromethane, and then methanol was added to precipitate to obtain bio-based polycarbonate (PIC).

[0045] After the catalytic experiment, a gas chromatograph was used for detection. The percentage content of each component in the product was determined by the area normalization method, and the conversion rates and yields of the reactants and the target product were calculated. The product was measured with an Ubbelohde viscometer, and the viscosity-average molecular weight was estimated by the one-point method. The catalytic results are shown in Table 1.

[0046] Example 2

[0047] Preparation of Catalyst 1,3-(p-toluic acid Zinc Salt)Im CuCl3

[0048] (1) Preparation of Intermediate I

[0049] 0.2 mol of 4-(chloromethyl)benzoic acid and 0.12 mol of imidazole were added to a rotating packed bed reactor, and the reaction was carried out without a solvent at 25 °C for 3 h. After the reaction ended, suction filtration was carried out, and it was washed and dried to obtain Intermediate I with a yield of 89%.

[0050] (2) Preparation of Intermediate II

[0051] 0.08 mol of Intermediate I and 0.018 mol of zinc nitrate were added to an essence kettle, 50 mL of deionized water was added, and the mixture was heated in an oven at 110 °C for 16 h. After stopping heating, it was naturally cooled for 14 h. After suction filtration, stirring and washing, and vacuum drying, Intermediate II was obtained with a yield of 93%.

[0052] (3) Preparation of the target catalyst

[0053] 0.12 mol of Intermediate II and 0.13 mol of copper chloride were added to a molecular reactor, 80 mL of distilled water was added as a solvent, and the reaction was carried out in a vacuum environment at 35 °C for 15 h. After the reaction ended, it was filtered, washed, and dried to obtain the target product with a yield of 95%.

[0054] The metal cation-anion coordination ionic liquid catalyst prepared above was used to catalyze the reaction of diphenyl carbonate and isosorbide to synthesize bio-based polycarbonate. The catalytic process conditions and the catalytic process were the same as those in Example 1, where the molar ratio of diphenyl carbonate to isosorbide was 1.1:1.

[0055] Example 3

[0056] Preparation of catalyst 1,3-(p-toluic acid Zinc Salt)Im FeCl3

[0057] (1) Preparation of Intermediate I

[0058] 0.08 mol of 4-(chloromethyl)benzoic acid and 0.038 mol of imidazole were added to a rotating packed bed reactor, and the reaction was carried out in a solvent-free environment at 25 °C for 6 h. After the reaction ended, suction filtration was carried out, and after washing and drying, Intermediate I was obtained with a yield of 80%.

[0059] (2) Preparation of Intermediate II

[0060] 0.2 mol of Intermediate I and 0.052 mol of zinc nitrate were added to an essence kettle, 23 mL of deionized water was added, and the mixture was heated in an oven at 90 °C for 22 h. After stopping heating, it was naturally cooled for 8 h. After suction filtration, stirring and washing, and vacuum drying, Intermediate II was obtained with a yield of 68%.

[0061] (3) Preparation of the target catalyst

[0062] 0.01 mol of Intermediate II and 0.015 mol of ferric chloride were added to a molecular reactor, 30 mL of distilled water was added as a solvent, and the reaction was carried out in a vacuum environment at 67 °C for 5 h. After the reaction ended, it was filtered, washed, and dried to obtain the target product with a yield of 98%.

[0063] The metal cation and anion coordinated ionic liquid catalyst prepared above was used to catalyze the reaction of diphenyl carbonate and isosorbide to synthesize bio-based polycarbonate. The catalytic process conditions and the catalytic process were the same as those in Example 1, where the molar ratio of diphenyl carbonate to isosorbide was 1:1.

[0064] In addition, traditional catalysts copper phosphate and zinc nitrate were respectively used to catalyze the reaction of diphenyl carbonate and isosorbide to synthesize bio-based polycarbonate. The catalytic process conditions and the catalytic process were the same as those in the above Example 1. The effects of different catalyst types on the catalytic performance were investigated, and the catalytic results are shown in Table 1.

[0065] Table 1 Effects of catalyst types on catalytic performance

[0066] Catalyst type Conversion rate (%) Yield (%) Mv Mw Copper phosphate 76.13 64.71 13203 23516 Zinc nitrate 74.44 63.14 11274 20929 Example 1 99.13 98.21 39899 54447 Example 2 93.24 90.44 31862 45392 Example 3 94.28 91.61 33991 48186

[0067] (Mv is the viscosity-average molecular weight, and Mw is the weight-average molecular weight)

[0068] It can be seen from the data in Table 1 that the catalyst of the present invention has a significant catalytic effect. Compared with the traditional catalyst, the reaction conversion rate and yield of the ionic liquid catalyst prepared in the present invention are both greatly improved. Among them, the catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3 prepared in Example 1 has the best catalytic effect, with a conversion rate as high as 99.13% and a yield as high as 98.21%.

[0069] a is intermediate II, and b is 1,3-(p-toluic acid Zinc Salt)Im ZnCl3).

[0070] Figure 2 The chemical structures of the catalysts 1 (PIC-1) and 3-(p-toluic acid Zinc Salt)Im ZnCl3 prepared in Example 1 were tested by a Fourier transform infrared spectrometer (FT-IR). The stretching vibration frequency range of C-H on the imidazole ring was around 3063 cm -1 The double bond stretching vibration absorption peaks of C=C and C=N on the imidazole ring were respectively at 1629 cm -1 , 1445 cm -1 around. The stretching vibration absorption peak of C-H on the benzene ring was around 3063 cm -1 The C=C skeletal vibration peaks were at 1767 cm -1 , 1586 cm -1 , 1375 cm -1 , 1254 cm -1 around, verifying that the structure of the catalyst was correct.

[0071] Figure 3The catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3 prepared in Example 1 was subjected to a comparative test of crystallization of Intermediate II by means of an X-ray spectrometer (XRD). The peak positions of the diffraction peaks of the imidazole ring were found to be around 12.78, 20.27, 21.12, and 28.26, the peak positions of the diffraction peaks of 4-chloromethylbenzoic acid were around 14.55, 16.50, 26.61, and 30.77, and the peak positions of the diffraction peaks of metallic zinc were around 18.10, 23.54, and 27.75. By comparing the peak positions of Intermediate II (a) and 1,3-(p-toluic acid Zinc Salt)Im ZnCl3 (b), it was found that the peak value of the diffraction peak of metallic zinc was significantly sharpened and enhanced after the reaction of Intermediate II with zinc chloride, proving an increase in the content of metallic zinc and no obvious change in the organic structure, that is, the target catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3 was successfully synthesized.

[0072] Figure 4 The catalyst 1,3-(p-toluic acid Zinc Salt)Im ZnCl3 prepared in Example 1 was subjected to a thermal stability test by means of a thermogravimetric analyzer (TG). Figure 4 In this, a is Intermediate II and b is 1,3-(p-toluic acid Zinc Salt)Im ZnCl3; the obtained thermogravimetric curve is roughly divided into two stages. The first stage starts to decompose at around 100 °C, and the mass loss fraction is less than 10%, which is the stage of thermal volatilization of the residual solvent in the sample. The second stage starts to decompose at around 350 °C and completely decomposes at around 530 °C, and the mass residue rate remains at about 25%. The results show that the catalyst has good thermal stability and meets the requirements of the experimental conditions.

[0073] Example 5

[0074] The catalyst prepared in Example 1 was used to catalyze the synthesis of bio-based polycarbonate from diphenyl carbonate and isosorbide, and the catalyst dosage was changed to 0.2% of the total mass of the reactants. Other steps for synthesizing bio-based polycarbonate were the same as those in Example 1. The experimental results are shown in Table 2.

[0075] Example 6

[0076] The catalyst prepared in Example 1 was used to catalyze the synthesis of bio-based polycarbonate from diphenyl carbonate and isosorbide, and the catalyst dosage was changed to 0.6% of the total mass of the reactants. Other steps for synthesizing bio-based polycarbonate were the same as those in Example 1. The experimental results are shown in Table 2.

[0077] Table 2 Catalytic performance evaluation of Examples 5 - 6

[0078]

[0079] (Mv is the viscosity average molecular weight, Mw is the weight average molecular weight)

[0080] As can be seen from the data in Table 2, Example 1 has the best catalytic effect. Therefore, the preferred catalyst dosage is 0.4% of the total mass of the reactants. The corresponding reaction has a conversion rate of up to 99.13%, a yield of up to 98.21%, and a molecular weight exceeding 0.4%. This is because the reaction is reversible. Within a certain concentration range, increasing the amount of catalyst provides more active centers. When the concentration exceeds a certain level, the reverse reaction rate is accelerated, reducing the conversion rate. Therefore, the most suitable catalyst dosage is 0.4%.

[0081] Example 7

[0082] In this example, the raw material isosorbide in Example 1 was replaced with traditional bisphenol A, and then polycarbonate was synthesized with diphenyl carbonate. The reaction process and process conditions were the same as in Example 1. The differences in the preparation of polycarbonate using isosorbide and traditional bisphenol A as raw materials with diphenyl carbonate were investigated. The experimental results are shown in Table 4.

[0083] Table 4 Evaluation of catalytic effect of Examples 1 and 7

[0084]

[0085]

[0086] (Mv is the viscosity average molecular weight, Mw is the weight average molecular weight)

[0087] As can be seen from the data in Table 4, the conversion rate and yield of the bio-based polycarbonate synthesized using isosorbide as a raw material are not significantly different from those of the polycarbonate synthesized using bisphenol A as a traditional raw material, and the molecular weight meets the requirements. This indicates that the bio-based polycarbonate prepared by using isosorbide as a raw material instead of bisphenol A in the present invention meets the required quality indicators and can replace traditional bisphenol A polycarbonate in the field of plastic products, thereby solving the toxicity problem of bisphenol A polycarbonate, which is of great significance.

[0088] The chemical structures of the polycarbonate products prepared by Examples 1-3 and the conventional catalyst zinc acetate were characterized by Fourier transform infrared spectroscopy (FT-IR). Figure 5 The thermal properties of the product PC prepared in Example 7 and the product PC prepared in Example 1-3 were tested using a thermogravimetric analyzer (TG) and a differential scanning calorimeter (DSC). The results were as follows: Figure 6 , Figure 7 . Gel permeation chromatography (GPC), hydrogen nuclear magnetic resonance spectrometer ( 1 The molecular weight and chemical structure of the polycarbonate product obtained in Example 1 were tested and analyzed by H-NMR. The results are as follows: Figure 8and Figure 9 。

[0089] Figure 5 The structural comparison test of the prepared product PC was carried out by Fourier transform infrared spectrometer (FT-IR), and the results are as follows Figure 5 shown. In the figure, a is the product of zinc acetate, b is the product of Example 1, c is the product of Example 2, and d is the product of Example 3; the stretching vibration absorption peak of -OH on the isosorbide of the polymer becomes smaller at 3618 cm -1 and a stretching vibration absorption peak of the carbonate group C=O appears at 1748 cm -1 , and the stretching vibration peak of O-C-O at about 1237 cm -1 is enhanced, proving that the structure of the polymer is correct.

[0090] Figure 6 The thermal stability test of the synthesized polycarbonate prepared in Example 1 and Example 7 was carried out by thermogravimetric analyzer (TG), and the results are as follows Figure 6 shown, where PC is the product of Example 7 and PIC is the product of Example 1; as shown in the figure, the mass loss fractions of the PIC product and the PC standard sample are lower than 5% at 312 °C and 339 °C, and their thermal stabilities are similar.

[0091] Figure 7 The thermodynamic test of the synthesized polycarbonate prepared in Example 7 and Examples 1-3 was carried out by differential scanning calorimeter (DSC), where PC is the product of Example 7, PIC-3 is the product of Example 1, PIC-2 is the product of Example 2, and PIC-1 is the product of Example 3; as Figure 7 shown, by comparing the glass transition temperatures of the synthesized PC and PIC, the glass transition temperature of PIC is about 170 °C, which is higher than that of the PC standard sample at 149 °C, further proving that their thermal properties are similar.

[0092] Figure 8 The molecular weight test of the polycarbonate synthesized in Example 1 was carried out by gel permeation chromatography (GPC), and the results are as follows Figure 8 shown. The number average molecular weight is at most 24,866, the peak top molecular weight is 43,440, the molecular weight distribution coefficient is 2.18, and the weight average molecular weight is 54,447. They are all close to the standards of commercially available polycarbonate.

[0093] Figure 9 The nuclear magnetic test of the polycarbonate synthesized in Example 1 was carried out by hydrogen nuclear magnetic resonance spectroscopy ( 1 1H-NMR), and the results are as follows Figure 9As shown, the peak positions corresponding to the hydrogens of H-1, H-2, H-3, H-4, H-5, and H-6 in the polymer unit are around 3.99 ppm, 4.99 ppm, 4.83 ppm, 4.83 ppm, 5.06 ppm, and 3.83 ppm respectively. The peak positions corresponding to the hydrogens of H-c and H-d on the benzene ring of the end group DPC are 7.18 ppm and 7.44 ppm respectively. There are two different hydroxyl hydrogens (outer hydroxyl H-a' and inner hydroxyl H-a) on the end group ISO at around 4.24 ppm and 4.22 ppm respectively, and H-b on the end group ISO is around 4.49 ppm, 4.44 ppm, and 4.41 ppm. Therefore, it can be proved that the structure of the PIC sample is correct and the experimental synthesis is successful.

Claims

1. Application of a catalyst in the synthesis of bio-based polycarbonate by transesterification and polycondensation of isosorbide and diphenyl carbonate; The catalyst is a metal cation-anion coordination ionic liquid catalyst with the following structure: ； Me = Zn, Cu, Fe.

2. The application of the catalyst according to claim 1, wherein: The application method is as follows: Under atmospheric pressure, isosorbide, diphenyl carbonate and the catalyst are mixed and put into a reaction kettle. The molar ratio of diphenyl carbonate to isosorbide is 1 - 1.1:

1. It is heated to 150 °C and maintained at this temperature for 0.5 h. Then, the reaction temperature is raised from 150 °C to 165 - 185 °C, and the pressure is reduced to 2 - 6 kPa to carry out the transesterification reaction for 20 - 60 min, and the by-product phenol is removed by decompression. Thereafter, the temperature is gradually raised to 210 - 250 °C, the pressure is reduced to 5 kPa - 100 Pa, and the polycondensation reaction is carried out for 0.5 - 4 h. The reaction ends to obtain the final product bio-based polycarbonate.

3. Use of the catalyst according to claim 2, characterized in that: The catalyst dosage is 0.2 - 0.6% of the total mass of the reactants.

4. Use of the catalyst according to claim 3, characterized in that: The catalyst dosage is 0.4% of the total mass of the reactants.

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