Bio-based polycarbonate and preparation method thereof

Abstract

The invention discloses bio-based polycarbonate and a preparation method thereof, and belongs to the technical field of high polymer materials. The method comprises the following steps: dissolving isosorbide in an organic solvent, adding a catalyst, continuously introducing carbon dioxide, carrying out condensation polymerization at specific temperature and pressure, and after the reaction is finished, precipitating, washing and drying to obtain a finished product. By optimizing reaction conditions, the biomass source proportion of the material is increased, the hardness and mechanical properties of the material are remarkably improved, and a feasible technical scheme is provided for replacing traditional bisphenol A polycarbonate.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a bio-based polycarbonate directly polycondensed from isosorbide and carbon dioxide and a preparation method thereof. Background Art

[0002] As an important polymer material, polycarbonate is widely used in the fields of electronics, automobiles, architecture, etc. due to its excellent mechanical properties, thermal stability and transparency. However, traditional polycarbonate materials have problems such as low biomass content, insufficient hardness and poor environmental friendliness. Especially bisphenol A type polycarbonate has been increasingly restricted and in need of replacement in recent years due to the potential harm of its raw material bisphenol A to human health and the environment. To solve these problems, researchers have begun to explore ways to prepare polycarbonate using bio-based raw materials to improve the sustainability and environmental protection performance of the materials.

[0003] As a diol monomer derived from biomass, isosorbide is considered an ideal alternative raw material due to its rigid structure and renewable characteristics. Compared with traditional bisphenol A, isosorbide not only has a higher biomass content but also can endow polycarbonate with higher hardness and thermal stability.

[0004] Therefore, developing an efficient, environmentally friendly method for preparing high-performance bio-based polycarbonate has become an important research direction in the field of polymer materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide a bio-based polycarbonate with high biomass content and high hardness and a preparation method thereof.

[0006] The technical solution adopted by the present invention to solve its technical problems is: the bio-based polycarbonate has the following structural formula:

[0007] ; the above bio-based polycarbonate is polymerized from isosorbide and carbon dioxide through a polycondensation reaction, and the bio-based content is higher than 70%.

[0008] The present invention directly polycondenses isosorbide and carbon dioxide to prepare a bio-based polycarbonate. Both the isosorbide and carbon dioxide used can be prepared from bio-based sources, which not only increases the proportion of biomass sources of the material but also significantly improves its hardness and mechanical properties, providing a feasible technical solution for replacing traditional bisphenol A type polycarbonate.

[0009] A preparation method of the above bio-based polycarbonate, the synthesis route includes:

[0010] .

[0011] Specifically, the specific method is as follows: Dissolve isosorbide in an organic solvent, add a hydroxyl activator, continuously introduce carbon dioxide, dropwise add a basic catalyst to the reaction system, and carry out a polycondensation reaction under pressure at room temperature (25 °C) or under heating conditions. After the reaction is completed, the product is obtained through precipitation, washing, and drying.

[0012] Under the action of a large amount of hydroxyl activator and basic catalyst in the present invention, the direct reaction of isosorbide and carbon dioxide is realized, and bio-based polyisosorbide carbonate is prepared, reducing the raw material cost and carbon footprint, and overcoming the dependence on petroleum raw materials. If only isosorbide is prepared from bio-based raw materials, the bio-based content is higher than 70%; if carbon dioxide is also prepared from bio-based raw materials, the bio-based content of the raw materials can reach 100%.

[0013] Preferably, the organic solvent includes acetonitrile, N,N-dimethylformamide or N-methylpyrrolidone. These solvents can effectively dissolve isosorbide and provide a good reaction environment during the reaction.

[0014] Preferably, the hydroxyl activator includes p-toluenesulfonyl chloride, bromoethane or dibromomethane. p-Toluenesulfonyl chloride, bromoethane and dibromomethane can convert the hydroxyl group of isosorbide into a derivative with an excellent leaving group (sulfonate or haloalkyl ether) through sulfonylation or etherification / alkylation, thereby significantly improving the reactivity of the hydroxyl group, especially its ability as a leaving group or introducing excellent leaving groups in its vicinity, thus greatly promoting the subsequent formation of carbonate bonds with carbon dioxide in the polycondensation reaction.

[0015] The basic catalyst includes triethylamine, cesium carbonate, pyridine, DBU, TMP. They not only provide basic conditions (neutralize acids and activate hydroxyl groups into RO⁻), but more importantly, they play a catalytic role in activating CO2 and promoting the nucleophilic addition reaction between CO2 and alkoxide / activated intermediates.

[0016] Preferably, the heating temperature is 180 °C to 250 °C, and the pressure is increased by carbon dioxide to 1.1 MPa to 4.0 MPa. This temperature and pressure range can ensure the efficient progress of the reaction, avoid side reactions, ensure the full participation of carbon dioxide in the reaction, and avoid too high or too low carbon dioxide concentration in the reaction system.

[0017] Preferably, the molar ratio of isosorbide to the hydroxyl activator is 1:1 to 3; the molar ratio of isosorbide to the basic catalyst is 1:1 to 5. The molar ratio of isosorbide to the hydroxyl activator ensures sufficient site activation. An excessive amount of the activator can overcome the steric hindrance effect of the dihydroxyl groups in the isosorbide molecule, improve the efficiency of converting hydroxyl groups into sulfonate esters or haloethers, and lay the foundation for the subsequent formation of carbonate bonds; meanwhile, it compensates for the consumption of possible side reactions. More preferably, the molar ratio of isosorbide to the hydroxyl activator is 1:1.5 to 2.5. The wide range of ratios of isosorbide to the basic catalyst provides operational flexibility. Sufficient or excessive base can not only effectively neutralize the strong acids (HCl / HBr) by-produced in sulfonylation or alkylation to prevent the degradation of the polymer chain, but also provide a highly basic environment to maintain the concentration of alkoxide anions, continuously activate the introduced CO2 and catalyze its insertion reaction. This ratio range synergistically promotes the chain growth polycondensation reaction with high conversion rate, which is beneficial to the synthesis of polycarbonate products with high molecular weight and controllable structure.

[0018] Preferably, the polycondensation reaction time is 1 to 12 hours. This reaction time can ensure the full progress of the reaction and avoid the occurrence of side reactions due to too long reaction time.

[0019] Preferably, the precipitant for the precipitation is methanol, ethanol or acetone. These precipitants can effectively precipitate the reaction products, facilitating subsequent washing and drying operations.

[0020] Preferably, the drying temperature is 40°C to 80°C, and the drying time is 2 to 24 hours. These drying conditions can ensure the full drying of the reaction products and avoid the influence of high temperature on the product performance.

[0021] Specifically, in the above preparation method of the bio-based polycarbonate, the dosage of the organic solvent is 5 to 20 times the mass of isosorbide. This dosage can ensure the full dissolution of isosorbide in the solvent and avoid the influence of excessive solvent on the reaction.

[0022] Specifically, in the above preparation method of the bio-based polycarbonate, the stirring speed of the polycondensation reaction is 100 to 500 revolutions per minute. This stirring speed can ensure the uniformity of the reaction system and avoid the influence of too fast or too slow stirring speed on the reaction.

[0023] Specifically, in the above preparation method of the bio-based polycarbonate, the dosage of the precipitant is 2 to 10 times the volume of the reaction solution. This dosage can ensure the full precipitation of the reaction products and avoid the influence of excessive precipitant on the products.

[0024] Specifically, in the above method for preparing the bio-based polycarbonate, the number of washing times is 2 to 5 times, and the amount of water used for each washing is 2 to 5 times the mass of the precipitate. Such washing conditions can ensure the sufficient washing of the reaction product while avoiding the influence of excessive or insufficient washing times on the product.

[0025] Specifically, in the above method for preparing the bio-based polycarbonate, the water content of the dried finished product is less than 1%. Such water content can ensure the stability and performance of the product.

[0026] Specifically, in the above method for preparing the bio-based polycarbonate, the molecular weight of the finished product is 1000 g / mol to 100000 g / mol. Such molecular weight range can ensure that the product has good mechanical properties and thermal stability.

[0027] Compared with the prior art, the present invention has the following beneficial effects: The present invention directly polycondenses isosorbide with carbon dioxide to prepare bio-based polycarbonate, which not only increases the proportion of biomass source of the material, but also significantly improves its hardness and mechanical properties, providing a feasible technical solution for replacing traditional bisphenol A polycarbonate. Detailed implementation manners

[0028] The present invention will be specifically described below through examples. Unless otherwise stated, all raw materials used are commercially available.

[0029] Example 1

[0030] Isosorbide, acetonitrile, and p-toluenesulfonyl chloride were added to a reaction kettle. The molar ratio of isosorbide to p-toluenesulfonyl chloride was 1:1, and the amount of acetonitrile used was 5 times the mass of isosorbide. Carbon dioxide was continuously introduced at room temperature until the pressure reached 2.5 MPa. Triethylamine was added dropwise to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:1 for polycondensation reaction. The stirring speed was 300 revolutions per minute, and the reaction time was 12 hours. After the reaction ended, the bio-based polycarbonate was obtained through methanol precipitation, washing, and drying. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate was measured by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 97.8%.

[0031] Example 2

[0032] Add isosorbide, N,N-dimethylformamide, and bromoethane into a reaction kettle. The molar ratio of isosorbide to bromoethane is 1:2, and the dosage of N,N-dimethylformamide is 10 times the mass of isosorbide. Heat up to 100 °C, continuously introduce carbon dioxide until the pressure reaches 2.0 MPa, and add triethylamine dropwise to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:2 for polycondensation reaction. The stirring speed is 300 revolutions per minute, the reaction time is 6 hours. After the reaction, obtain the bio-based polycarbonate through ethanol precipitation, washing, and drying. Immediately determine by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is 97.7%.

[0033] Example 3

[0034] Add isosorbide, N-methylpyrrolidone, and dibromomethane into a reaction kettle. The molar ratio of isosorbide to dibromomethane is 1:5, and the dosage of N-methylpyrrolidone is 20 times the mass of isosorbide. Heat up to 200 °C, continuously introduce carbon dioxide until the pressure reaches 2.5 MPa, and add triethylamine dropwise to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:3 for polycondensation reaction. The stirring speed is 300 revolutions per minute, the reaction time is 1 hour. After the reaction, obtain the bio-based polycarbonate through acetone precipitation, washing, and drying. Immediately determine by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is 98.0%.

[0035] Example 4

[0036] Add isosorbide, acetonitrile, and p-toluenesulfonyl chloride into a reaction kettle. The molar ratio of isosorbide to p-toluenesulfonyl chloride is 1:3, and the dosage of acetonitrile is 15 times the mass of isosorbide. Heat up to 50 °C, continuously introduce carbon dioxide until the pressure reaches 2 MPa, and add triethylamine dropwise to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:5 for polycondensation reaction. The stirring speed is 300 revolutions per minute, the reaction time is 8 hours. After the reaction, obtain the bio-based polycarbonate through methanol precipitation, washing, and drying. Immediately determine by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is 96.4%.

[0037] Example 5

[0038] Add isosorbide, N,N-dimethylformamide, and bromoethane into the reaction kettle. The molar ratio of isosorbide to bromoethane is 1:4, and the dosage of N,N-dimethylformamide is 12 times the mass of isosorbide; heat up to 150 °C, continuously introduce carbon dioxide until the pressure reaches 2.0 MPa, and dropwise add triethylamine to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:5 for polycondensation reaction. The stirring speed is 300 revolutions per minute, the reaction time is 3 hours. After the reaction is completed, the bio-based polycarbonate is obtained by precipitation with ethanol, washing, and drying. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is determined by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 88.6%.

[0039] Example 6

[0040] Add isosorbide, N-methylpyrrolidone, and dibromomethane into the reaction kettle. The molar ratio of isosorbide to dibromomethane is 1:2, and the dosage of N-methylpyrrolidone is 18 times the mass of isosorbide; heat up to 80 °C, continuously introduce carbon dioxide until the pressure reaches 2.5 MPa, and dropwise add triethylamine to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:1 for polycondensation reaction. The stirring speed is 300 revolutions per minute, the reaction time is 4 hours. After the reaction is completed, the bio-based polycarbonate is obtained by precipitation with acetone, washing, and drying. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is determined by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 92.4%.

[0041] Example 7

[0042] Add isosorbide, acetonitrile, and p-toluenesulfonyl chloride into the reaction kettle. The molar ratio of isosorbide to p-toluenesulfonyl chloride is 1:5, and the dosage of acetonitrile is 20 times the mass of isosorbide; heat up to 120 °C, continuously introduce carbon dioxide until the pressure reaches 1.5 MPa, and dropwise add triethylamine to the reaction system according to the molar ratio of isosorbide to triethylamine of 1:1 at a rate of 60 milliliters per minute. The stirring speed is 300 revolutions per minute for polycondensation reaction, and the reaction time is 10 hours. After the reaction is completed, the bio-based polycarbonate is obtained by precipitation with methanol, washing, and drying. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is determined by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 93.5%.

[0043] Example 8

[0044] Isosorbide, N,N-dimethylformamide, and bromoethane were added to a reaction kettle. The molar ratio of isosorbide to bromoethane was 1:1, and the amount of N,N-dimethylformamide used was 8 times the mass of isosorbide. The temperature was raised to 70 °C, and carbon dioxide was continuously introduced until the pressure reached 4 MPa. Triethylamine was added dropwise to the reaction system at a molar ratio of isosorbide to triethylamine of 1:1 for polycondensation reaction. The stirring speed was 100 revolutions per minute, and the reaction time was 2 hours. After the reaction, the product was precipitated with ethanol, washed, and dried to obtain a bio-based polycarbonate. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate was measured immediately by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 84.3%.

[0045] Example 9

[0046] Isosorbide, N-methylpyrrolidone, and dibromomethane were added to a reaction kettle. The molar ratio of isosorbide to dibromomethane was 1:3, and the amount of N-methylpyrrolidone used was 16 times the mass of isosorbide. The temperature was raised to 180 °C, and carbon dioxide was continuously introduced until the pressure reached 1.5 MPa. Cesium carbonate was added dropwise to the reaction system at a molar ratio of isosorbide to cesium carbonate of 1:1 for polycondensation reaction. The stirring speed was 500 revolutions per minute, and the reaction time was 11 hours. After the reaction, the product was precipitated with acetone, washed, and dried to obtain a bio-based polycarbonate. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate was measured immediately by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 88.7%.

[0047] Example 10

[0048] Isosorbide, acetonitrile, and p-toluenesulfonyl chloride were added to a reaction kettle. The molar ratio of isosorbide to p-toluenesulfonyl chloride was 1:2, and the amount of acetonitrile used was 10 times the mass of isosorbide. The temperature was raised to 60 °C, and carbon dioxide was continuously introduced until the pressure reached 2.5 MPa. TMP was added dropwise to the reaction system at a molar ratio of isosorbide to TMP of 1:1 at a feeding rate of 50 mL per minute for polycondensation reaction. The stirring speed was 300 revolutions per minute, and the reaction time was 5 hours. After the reaction, the product was precipitated with methanol, washed, and dried to obtain a bio-based polycarbonate. The mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate was measured immediately by nuclear magnetic resonance and Fourier transform infrared spectroscopy to be 97.8%.

[0049] The performance comparison of the bio-based polycarbonates prepared in the examples of the present invention is shown in Table 1. Among them, the glass transition temperature (Tg) was measured by differential scanning calorimetry (DSC), the tensile strength and elongation at break were tested according to the ISO 527 standard, and the Rockwell hardness was tested according to the ASTM D785 standard.

[0050] Table 1

[0051] Example Tg (°C) Tensile strength (MPa) Elongation at break (%) Rockwell hardness (R scale) Example 1 123 65 15 118 Example 2 125 70 18 120 Example 3 130 85 8 125 Example 4 115 60 20 115 Example 5 112 48 35 105 Example 6 128 55 25 110 Example 7 116 63 17 117 Example 8 109 40 50 98 Example 9 127 75 12 122 Example 10 128 80 10 124

[0052] The Tg values of the embodiments of the present invention are much higher than those of traditional carbon dioxide copolymerized polycarbonates, which is due to the rigid furan ring structure of isosorbide.

[0053] The above are only the preferred embodiments of the present invention, and are not limitations on the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A bio-based polycarbonate, characterized in that, The structural formula is: ; It is polymerized from isosorbide and carbon dioxide through a polycondensation reaction, and the bio-based content is higher than 70%.

2. A method for preparing the bio-based polycarbonate according to claim 1, characterized in that, The synthesis route includes: 。 3. The preparation method of a bio-based polycarbonate according to claim 2, characterized in that, The specific method is as follows: Dissolve isosorbide in an organic solvent, add a hydroxyl activator, continuously introduce carbon dioxide, dropwise add a basic catalyst to the reaction system, and carry out a polycondensation reaction under pressure at room temperature or heating conditions. After the reaction is completed, the product is obtained through precipitation, washing, and drying.

4. The preparation method of a bio-based polycarbonate according to claim 3, characterized in that, The organic solvents described include acetonitrile, N,N-dimethylformamide, or N-methylpyrrolidone; the hydroxyl activators described include p-toluenesulfonyl chloride, bromoethane, or dibromomethane; the basic catalysts described include triethylamine, cesium carbonate, pyridine, DBU, and TMP.

5. The preparation method of a bio-based polycarbonate according to claim 3, characterized in that, The temperature of the heating is 180°C to 250°C, and the pressure is increased by carbon dioxide to 1.1 MPa to 4.0 MPa.

6. The preparation method of a bio-based polycarbonate according to claim 3, characterized in that, The molar ratio of the isosorbide to the hydroxyl activator is 1:1 to 3; the molar ratio of the isosorbide to the basic catalyst is 1:1 to 5.

7. According to the preparation method of a bio-based polycarbonate described in claim 3, the polycondensation reaction time is 1 to 12 hours.

8. According to the preparation method of a bio-based polycarbonate described in claim 3, the precipitant for the precipitation is methanol, ethanol, or acetone.

9. According to the preparation method of a bio-based polycarbonate described in claim 3, the drying temperature is 40°C to 80°C, and the drying time is 2 to 24 hours.

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