Method for preparing polycarbonate through catalysis of quaternary ammonium eutectic solvent

Abstract

The invention belongs to the field of catalysis, organic synthesis and high polymer materials, and discloses a method for preparing polycarbonate through catalysis of a quaternary ammonium eutectic solvent. According to the preparation method, a diol monomer and a diester carbonate monomer are taken as raw materials, a quaternary ammonium eutectic solvent is taken as a catalyst, and the polycarbonate is synthesized through transesterification, a pre-polycondensation reaction and a final polycondensation reaction in a nitrogen atmosphere. The weight-average molecular weight of the obtained polycarbonate is 100000 to 200000 g / mol, the PDI is 1.2 to 1.8, and the yield is 85 to 98 percent. According to the method, the quaternary ammonium deep-eutectic solvent is adopted as a catalyst, the dihydroxy compound and the diester carbonate raw materials are efficiently activated through the synergistic effect of a hydrogen bond donor and a hydrogen bond receptor, and high catalytic activity is achieved; the used catalyst avoids the use of an alkali metal catalyst and is massively decomposed in the final polycondensation reaction process, so that the influence of catalyst residues on the product is reduced; the raw materials of the catalyst are green, low in cost and easy to obtain, the cost is low, and the polycarbonate is easy to synthesize, so that the method is an efficient, green and environment-friendly low-cost polycarbonate synthesis process.

Description

Technical Field

[0001] This invention relates to the fields of catalysis, organic synthesis and polymer materials, and in particular to a method for preparing polycarbonate using quaternary ammonium eutectic solvents. Background Technology

[0002] Polycarbonate is a class of polymeric materials containing carbonate groups in its molecular chain. Due to its excellent transmittance, impact resistance, and dimensional stability, it is widely used in automotive trim, aerospace, and electronics. Currently, polycarbonate preparation methods include the phosgene method and the non-phosgene melt transesterification method. The phosgene method uses highly toxic phosgene as its raw material and requires large amounts of organic solvents, resulting in significant environmental pollution. With the increasing prominence of environmental issues, newly established polycarbonate manufacturers are gradually adopting the environmentally friendly melt transesterification method, which completely eliminates the use of toxic phosgene and reagents. Because the melt transesterification method requires the continuous removal of small-molecule byproducts to promote the reaction, high temperature and low pressure are necessary. However, as the reaction temperature increases, side reactions such as branching, cross-linking, and degradation easily occur, leading to a decrease in the molecular weight and purity of the polycarbonate product, thus affecting subsequent applications. Therefore, developing novel catalytic systems that precisely activate monomers while suppressing side reactions such as monomer rearrangement is one of the effective strategies for obtaining high molecular weight, high-purity polycarbonate.

[0003] Currently, catalytic systems used for polycarbonate preparation mainly include alkali metal and organic base catalytic systems. For example, patent CN202111109227.6 discloses an alkali metal bicarbonate catalyst for polycarbonate preparation. By controlling the temperature, the catalytic effect was modulated from weak to strong, promoting transesterification and polymerization reactions while suppressing side reactions such as branching and crosslinking, thus achieving the preparation of high molecular weight polycarbonate with a narrow molecular weight distribution. The use of alkali metal catalysts can effectively activate diol monomers, and the catalytic activity is enhanced as the radius of the metal cation decreases and the electrophilicity increases. However, residual metal ions in the product can also cause increased yellowness and reduced thermal stability at high temperatures. Furthermore, the synthesis of polycarbonate using alkali metal catalysis still requires long reaction times and high temperatures, and the use of metal ions can cause environmental pollution. Patent CN202311431690.1 discloses a catalytic system for polycarbonate preparation, comprising one or more organic base catalysts selected from potassium methoxide, sodium methoxide, lithium methoxide, potassium acetate, and sodium acetate. This system achieves the preparation of bisphenol fluorene-based polycarbonate with a conversion rate as high as 98.7% and an intrinsic viscosity of 0.60 dL / g. CN202010037088.X discloses organic non-metallic catalysts for polycarbonate preparation, including nitrogen-containing organic compounds such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,1,3,3-tetramethylguanidine. These catalysts activate the hydroxyl groups of dihydroxy compounds, promoting transesterification between the dihydroxy compounds and diesters, resulting in safer and more widely applicable polycarbonates. Organic nonmetallic catalysts avoid the use of metal ions and reduce the impact of catalyst residues on polycarbonate products. However, their low reactivity, low selectivity, and long reaction time limit the application of organic base catalysts. With the development of green chemistry, ionic liquid systems (CN202011409275.2, CN202110003421.X, CN202011409275.2) have recently been developed for the preparation of polycarbonate, offering advantages such as high catalytic activity and environmental friendliness. However, ionic liquids are expensive and their synthesis process is relatively complex. Compared with ionic liquids, eutectic solvents, as a new generation of green solvents, combine the advantages of ionic liquids such as unique hydrogen bonding, physicochemical properties, low cost, and easy synthesis, making them more suitable for large-scale applications and providing a new approach to catalytic systems for polycarbonate preparation. However, polycarbonates prepared using existing technologies have low molecular weights, resulting in poor thermal and mechanical properties, mainly manifested in low glass transition temperature and thermal decomposition temperature, low tensile strength, and low elongation at break, severely limiting the multifaceted applications of the materials. Summary of the Invention

[0004] To address the issues of common alkali metal and organic base catalysts being prone to residue or having low activity, and the resulting polycarbonates having low molecular weights, this invention proposes a method for preparing polycarbonates using quaternary ammonium eutectic solvents. This catalytic system is adjustable in terms of pH, molecular size, and hydrogen bond network, enabling the efficient preparation of high molecular weight polycarbonates.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst includes the following steps: a glycol monomer and a carbonate diester monomer are mixed and heated under a nitrogen atmosphere until the substrate melts. Then, a quaternary ammonium eutectic solvent is added, and polycarbonate is obtained after transesterification, pre-condensation, and final condensation reactions.

[0007] The aforementioned quaternary ammonium eutectic solvents include hydrogen bond acceptors and hydrogen bond donors, with a molar ratio of (0.1-10):1. For example, the molar ratio of hydrogen bond acceptors to hydrogen bond donors is (0.1-2):1; for example, the molar ratio of hydrogen bond acceptors to hydrogen bond donors is (3-10):1; for example, the molar ratio of hydrogen bond acceptors to hydrogen bond donors is (0.1-4):1; for example, the molar ratio of hydrogen bond acceptors to hydrogen bond donors is 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1.

[0008] Furthermore, the hydrogen bond acceptor described above is selected from any one of the following structures:

[0009]

[0010] More preferably, the hydrogen bond acceptor is selected from any one of the following structures:

[0011]

[0012] The hydrogen bond donors mentioned above are selected from any of the following structures:

[0013]

[0014] The aforementioned diol monomers are any one of the following compounds: 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, isosorbide, isomannitol, isoidutol, 4,4'-dihydroxydiphenylmethane, 4,4'-cyclohexylbisphenol, and 4,4'-isopropylidene biphenol.

[0015] The aforementioned carbonate diester monomer is any one of dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and diphenyl carbonate.

[0016] The molar ratio of the above-mentioned diol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:(1-1.5):(1×10⁻⁶). -5 -1×10 -3 For example, the molar ratio of diol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:(1-1.3):(1×10⁻⁶). -5 -1×10 -4 For example, the molar ratio of glycol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:(1.4-1.5):(1×10⁻⁶). -4 -1×10 -3 For example, the molar ratio of glycol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:(1.2-1.4):(1×10⁻⁶). -5 -1×10 -2 For example, the molar ratio of diol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:1:(1×10⁻⁶). -5 -1×10 -3 ), 1:1.1:(1×10 -5 -1×10 -3 ), 1:1.2:(1×10 -5 -1×10 -3 ), 1:1.3:(1×10 -5 -1×10 -3 ), 1:1.4:(1×10 -5 -1×10 -3 ), 1:1.5:(1×10 -5 -1×10 -3 The range of values ​​formed by any two values ​​in the range; for example, the molar ratio of diol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:(1-1.5):1×10 -5 1:(1-1.5):5×10 -5 1:(1-1.5):1×10 -4 1:(1-1.5):5×10 -4 1:(1-1.5):1×10 -3 The range of values ​​formed by any value or any two values ​​in the range.

[0017] The transesterification reaction temperature is 100-200℃, the reaction time is 10 min-2 h, and the reaction pressure is atmospheric pressure. For example, the transesterification reaction temperature is 100-150℃, the reaction time is 1 min-2 h, and the reaction pressure is atmospheric pressure; for example, the transesterification reaction temperature is 150-200℃, the reaction time is 10 min-1 h, and the reaction pressure is atmospheric pressure; for example, the transesterification reaction temperature is 100-120℃, the reaction time is 1.5-1 h, and the reaction pressure is atmospheric pressure; for example, the transesterification reaction temperature is 130-150℃, the reaction time is 1-1.4 h, and the reaction pressure is atmospheric pressure; for example, the transesterification reaction temperature is 160-200℃, the reaction time is 10-50 min, and the reaction... The pressure should be atmospheric pressure; for example, the transesterification reaction temperature can be any value or any two values ​​from 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, and 200℃; the transesterification reaction time can be 10-120 min, for example, any value or any two values ​​from 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, and 120 min.

[0018] The prepolymerization reaction temperature is 220-280℃, the reaction time is 30 min-3 h, and the absolute reaction pressure is 20-80 Pa. The prepolymerization reaction temperature can be any value or any two of the following: 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, and 280℃. The prepolymerization reaction time can be any value or any two of the following: 30 min, 60 min, 90 min, 120 min, 150 min, and 180 min.

[0019] The final polycondensation reaction temperature is 220-280℃, the reaction time is 30 min-3 h, and the absolute reaction pressure is 50-1000 Pa. The polycondensation reaction temperature can be any value or any two of the following: 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, and 280℃. The reaction time can be any value or any two of the following: 30 min, 60 min, 90 min, 120 min, 150 min, and 180 min. The absolute reaction pressure can be any value or any two of the following: 50 Pa, 100 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa, and 1000 Pa.

[0020] More preferably, the pre-condensation reaction temperature is 240-250℃, the reaction time is 30 min, and the absolute reaction pressure is 20-80 Pa.

[0021] The polycarbonate prepared using the above method can have a weight-average molecular weight as high as 100,000-200,000 g·mol⁻¹. -1 .

[0022] Furthermore, the polycarbonate prepared using the above method can have a weight-average molecular weight as high as 155,100-197,600 g·mol⁻¹. -1 .

[0023] In the synthesis of polycarbonate using the aforementioned quaternary ammonium eutectic solvent catalysis, the cation in the hydrogen bond acceptor and the hydroxyl group in the hydrogen bond donor interact with the carbonyl group in the diester monomer, thereby activating the diester monomer. The anion in the hydrogen bond acceptor forms hydrogen bonds with the hydroxyl group in the glycol monomer, thus activating the glycol monomer. Furthermore, when isosorbide is used as the glycol monomer, the hydrogen bond acceptor can balance its internal and external hydroxyl groups, enhancing its reactivity. After the hydrogen bond donor and acceptor activate the substrate through hydrogen bond interactions, it promotes the attack of the glycol monomer on the carbonyl group of the diester monomer, thereby generating a substituted intermediate and byproducts. After vacuum removal of the byproducts, the intermediate condenses to form a long-chain, high-molecular-weight polycarbonate.

[0024] The beneficial effects of this invention are:

[0025] (1) The quaternary ammonium eutectic solvent described in this application can control its acidity, molecular size and hydrogen bond acidity by changing the structure and ratio of hydrogen bond acceptor and hydrogen bond donor. Through the synergistic action of hydrogen bond donor and hydrogen bond acceptor on the hydroxyl group of glycol monomer and carbonyl group of diester in eutectic solvent, the monomer is precisely activated, and high molecular weight polycarbonate with a weight average molecular weight of 100,000-200,000 g / mol is synthesized with a polymer dispersibility index (PDI) of 1.2-1.8 and a yield of 85-98%.

[0026] (2) The quaternary ammonium eutectic solvent used in this application can achieve good catalytic synthesis of polycarbonate with a small amount. In the melt transesterification reaction stage, the quaternary ammonium eutectic solvent has good stability and can escape from the reaction system in the later stage of polycondensation reaction, which is not easy to leave residue. This inhibits the occurrence of polycarbonate degradation reaction during the reaction process, thereby extending the service life of polycarbonate.

[0027] (3) The quaternary ammonium eutectic solvent used in this application is inexpensive, readily available, and simple to prepare. It is obtained by heating and stirring hydrogen bond acceptors and hydrogen bond donors in a predetermined molar ratio, without any further processing. The synthesized quaternary ammonium eutectic solvent has characteristics such as low melting point, low volatility, and low toxicity, and is a green catalyst with good prospects for industrial application. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] The polycarbonate yield of this invention is the ratio of the mass of polycarbonate obtained by melt polycondensation of diol monomers and diester monomers to the theoretical value.

[0030] The specific synthesis examples of the quaternary ammonium eutectic solvent catalyst of the present invention are as follows:

[0031] (1) Betaine-2(1,3-propanediol)

[0032] Take 40 mmol (4.69 g) of betaine (BET) and 80 mmol (6.09 g) of 1,3-propanediol (PDO) in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution, and remain a transparent solution after cooling to room temperature, to obtain the quaternary ammonium eutectic solvent betaine-2 (1,3-propanediol) (BET-2PDO).

[0033] (2) Betaine-2 (1,2,3,4-butanol)

[0034] Take 40 mmol (4.69 g) of BET and 80 mmol (9.77 g) of 1,2,3,4-butanol (ERY) in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent betaine-2 (1,2,3,4-butanol) (BET-2ERY).

[0035] (3) Betaine-2-ethylene glycol

[0036] Take 40 mmol (4.69 g) of BET and 80 mmol (4.97 g) of ethylene glycol (EG) in a 50 mL single-necked flask, heat at 80 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent betaine-2 ethylene glycol (BET-2EG).

[0037] (4) Choline-2 monoethanolamine chloride

[0038] Take 40 mmol (5.59 g) of choline chloride (ChCl) and 80 mmol (4.89 g) of monoethanolamine (ETA) in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution, and remain a transparent solution after cooling to room temperature to obtain the quaternary ammonium eutectic solvent choline chloride-2 monoethanolamine (ChCl-2ETA).

[0039] (5) Choline chloride-2-ethylene glycol

[0040] Take 40 mmol (5.59 g) of ChCl and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 60 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent choline chloride-2-ethylene glycol (ChCl-2EG).

[0041] (6) Choline chloride-2(1,3-propanediol)

[0042] Take 40 mmol (5.59 g) ChCl and 80 mmol (6.09 g) PDO in a 50 mL single-necked flask, heat at 80 °C for 2 h until the reactants are clear and transparent solutions. After cooling to room temperature, the solutions remain transparent, thus obtaining the quaternary ammonium eutectic solvent choline chloride-2 (1,3-propanediol) (ChCl-2PDO).

[0043] (7) Choline chloride-2 (1,2,3,4-butanol)

[0044] Take 40 mmol (5.59 g) ChCl and 80 mmol (9.77 g) ERY in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent choline chloride-2 (1,2,3,4-butanol) (ChCl-2ERY).

[0045] (8) Choline-2-diethanolamine chloride

[0046] Take 40 mmol (5.59 g) of ChCl and 80 mmol (8.41 g) of diethanolamine (DEA) in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent choline chloride-2-diethanolamine (ChCl-2DEA).

[0047] (9) L-Carnitine-2-Diethanolamine

[0048] 40 mmol (6.45 g) of L-carnitine (CAR-OH) and 80 mmol (8.41 g) of DEA were placed in a 50 mL single-necked flask and heated at 100 °C for 2 h until the reactants were a clear and transparent solution. After cooling to room temperature, the solution remained transparent, thus obtaining the quaternary ammonium eutectic solvent L-carnitine-2-diethanolamine (CAR-OH-2DEA).

[0049] (10) L-Carnitine-2 (D-Sorbitol)

[0050] Take 40 mmol (6.45 g) CAR-OH and 80 mmol (14.57 g) D-sorbitol (D-SOR) in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent L-carnitine-2 (D-sorbitol) (CAR-OH-2D-SOR).

[0051] (11) Triethylmethylammonium chloride-2(1,6-hexanediol)

[0052] Take 40 mmol (6.07 g) of triethylmethylammonium chloride (MTEAC) and 80 mmol (9.45 g) of 1,6-hexanediol (HDO) in a 50 mL single-necked flask, heat at 120 °C for 2 h until the reactants are a clear and transparent solution, and remain a transparent solution after cooling to room temperature, to obtain the quaternary ammonium eutectic solvent triethylmethylammonium chloride-2(1,6-hexanediol) (MTEAC-2HDO).

[0053] (12) Triethylmethylammonium chloride-2(1,3-propanediol)

[0054] Take 40 mmol (6.07 g) of triethylmethylammonium chloride (MTEAC) and 80 mmol (6.09 g) of PDO in a 50 mL single-necked flask, heat at 80 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent triethylmethylammonium chloride-2(1,3-propanediol) (MTEAC-2PDO).

[0055] (13) Triethylmethylammonium chloride-2-hydroquinone

[0056] Take 40 mmol (6.07 g) of triethylmethylammonium chloride (MTEAC) and 80 mmol (8.81 g) of hydroquinone (HQ) in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution, and remain a transparent solution after cooling to room temperature to obtain the quaternary ammonium eutectic solvent triethylmethylammonium chloride-2-hydroquinone (MTEAC-2HQ).

[0057] (14) Triethylmethylammonium chloride-4(1,10-decanediol)

[0058] 40 mmol (6.07 g) of triethylmethylammonium chloride (MTEAC) and 160 mmol (27.88 g) of 1,10-decanediol (DDO) were placed in a 50 mL single-necked flask and heated at 120 °C for 2 h until the reactants were a clear and transparent solution. After cooling to room temperature, the solution remained transparent, thus yielding the quaternary ammonium eutectic solvent triethylmethylammonium chloride-2(1,10-decanediol) (MTEAC-4DDO).

[0059] (15) Chlorocholine-2-ethylene glycol chloride

[0060] Take 40 mmol (6.32 g) of chlorocholine chloride (CCC) and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent chlorocholine-2-ethylene glycol (CCC-2EG).

[0061] (16) Chlorocholine-2-hydroquinone chloride

[0062] Take 40 mmol (6.32 g) of CCC and 80 mmol (8.81 g) of hydroquinone (HQ) in a 50 mL single-necked flask, heat at 120 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent chlorocholine-2-hydroquinone (CCC-2HQ).

[0063] (17) Chlorocholine-2-p-aminophenol chloride

[0064] 40 mmol (6.32 g) of CCC and 80 mmol (8.73 g) of p-aminophenol (AZQL) were placed in a 50 mL single-necked flask and heated at 100 °C for 2 h until the reactants were a clear and transparent solution. After cooling to room temperature, the solution remained transparent, thus obtaining the quaternary ammonium eutectic solvent chlorocholine-2-p-aminophenol (CCC-2AZQL).

[0065] (18) 2-Ethylene glycol tartrate

[0066] Take 40 mmol (10.13 g) of choline tartrate (ChTA) and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent choline tartrate-2-ethylene glycol (ChTA-2EG).

[0067] (19) Citrate-choline-2-ethylene glycol

[0068] Take 40 mmol (11.81 g) of citrate choline (ChCA) and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent citrate choline-2-ethylene glycol (ChCA-2EG).

[0069] (20) Nitrocholine-2-ethylene glycol

[0070] Take 40 mmol (6.65 g) of nitrate choline (ChNO3) - 80 mmol (4.97 g) of EG was placed in a 50 mL single-necked flask and heated at 100 °C for 2 h until the reactants formed a clear and transparent solution. The solution remained transparent after cooling to room temperature, yielding the quaternary ammonium eutectic solvent nitrate-choline-2-ethylene glycol (ChNO3). - -2EG).

[0071] (twenty one) Choline acetate-2-ethylene glycol

[0072] Take 40 mmol (6.53 g) of choline acetate (ChAc) and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent choline acetate-2-ethylene glycol (ChAc-2EG).

[0073] (twenty two) Benzyl dimethyl (2-hydroxyethyl)ammonium chloride-2-ethylene glycol

[0074] 40 mmol (8.63 g) of benzyl dimethyl (2-hydroxyethyl) ammonium chloride (BHD) and 80 mmol (4.97 g) of EG were placed in a 50 mL single-necked flask and heated at 100 °C for 2 h until the reactants were a clear and transparent solution. After cooling to room temperature, the solution remained transparent, thus yielding the quaternary ammonium eutectic solvent benzyl dimethyl (2-hydroxyethyl) ammonium chloride-2-ethylene glycol (BHD-2EG).

[0075] (twenty three) Benzoylcholine-2-ethylene glycol chloride

[0076] Take 40 mmol (9.75 g) of benzoylcholine chloride (ChBC) and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent benzoylcholine chloride-2-ethylene glycol (ChBC-2EG).

[0077] (twenty four) Tetrapropylammonium bromide-2-ethylene glycol

[0078] Take 40 mmol (10.65 g) of tetrapropylammonium bromide (PTAB) and 80 mmol (4.97 g) of EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent tetrapropylammonium bromide-2-ethylene glycol (PTAB-2EG).

[0079] (25) Benzyltriethylammonium chloride-2-ethylene glycol

[0080] Take 40 mmol (9.11 g) benzyltriethylammonium chloride (TEBA) and 80 mmol (4.97 g) EG in a 50 mL single-necked flask, heat at 100 °C for 2 h until the reactants are a clear and transparent solution. After cooling to room temperature, the solution remains transparent, thus obtaining the quaternary ammonium eutectic solvent benzyltriethylammonium chloride-2-ethylene glycol (TEBA-2EG).

[0081] Example 1

[0082] This embodiment describes a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The specific steps are as follows:

[0083] Ester exchange stage: Under normal pressure and nitrogen atmosphere, 0.1 mol (14.61 g) of isosorbide and 0.1 mol (21.42 g) of diphenyl carbonate were added to a four-necked flask, and the temperature was raised to 120 °C. After the raw materials were completely melted, 13.19 mg (5 × 10⁻⁶ molars of isosorbide) of quaternary ammonium eutectic solvent choline chloride-2-ethylene glycol (ChCl-2EG) was added. -5 The reaction was carried out for 1.5 hours. Pre-polymerization stage: the temperature was raised to 240℃, and the pressure was gradually reduced to vacuum (<50 Pa), reacting for a total of 1.5 hours. Final polymerization stage: the temperature was 240℃, and the pressure was reduced to vacuum (<100 Pa), reacting for 30 minutes. The synthesized isosorbide-based polycarbonate had a weight-average molecular weight of 162,000 g·mol⁻¹. -1 The PDI was 1.45, and the product yield was 95%.

[0084]

[0085] Example 2

[0086] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChCl-2PDO, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 162,700 g·mol⁻¹. -1 The PDI was 1.67, and the product yield was 91%.

[0087] Example 3

[0088] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChCl-2ERY, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 149,900 g·mol⁻¹. -1 The PDI was 1.52, and the product yield was 96%.

[0089] Example 4

[0090] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChCl-2ETA, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 140,400 g·mol⁻¹. -1 The PDI was 1.75, and the product yield was 93%.

[0091] Example 5

[0092] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChCl-2DEA, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 150,500 g·mol⁻¹. -1 The PDI was 1.69, and the product yield was 95%.

[0093] Example 6

[0094] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is BET-2EG, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 157,400 g·mol⁻¹. -1 The PDI was 1.68, and the product yield was 97%.

[0095] Example 7

[0096] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is BET-2ERY, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 143,900 g·mol⁻¹, a PDI of 1.74, and a product yield of 94%.

[0097] Example 8

[0098] This embodiment describes a method for preparing polycarbonate using a quaternary ammonium eutectic solvent catalysis. The difference from Example 1 is that the catalyst used is BET-2PDO, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 125,800 g·mol⁻¹, a PDI of 1.47, and a product yield of 98%.

[0099] Example 9

[0100] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is CAR-OH-2DEA, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 136,800 g·mol⁻¹. -1 The PDI was 1.29, and the product yield was 93%.

[0101] Example 10

[0102] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is CAR-OH-2D-SOR, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 146,400 g·mol⁻¹. -1The PDI was 1.28, and the product yield was 87%.

[0103] Example 11

[0104] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is MTEAC-4DDO, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 133,600 g·mol⁻¹. -1 The PDI was 1.35, and the product yield was 89%.

[0105] Example 12

[0106] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is MTEAC-2PDO, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 174,900 g·mol⁻¹. -1 The PDI was 1.23, and the product yield was 92%.

[0107] Example 13

[0108] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is MTEAC-2HQ, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 120-300 g·mol⁻¹. -1 The PDI was 1.78, and the product yield was 94%.

[0109] Example 14

[0110] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is CCC-2AZQL, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 150-600 g·mol⁻¹. -1 The PDI was 1.40, and the product yield was 91%.

[0111] Example 15

[0112] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChTA-2EG, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 197,600 g·mol⁻¹. -1 The PDI was 1.79, and the product yield was 95%.

[0113] Example 16

[0114] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChNO3-2EG, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 155100 g·mol⁻¹. -1 The PDI was 1.54, and the product yield was 85%.

[0115] Example 17

[0116] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is ChAc-2EG, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 137,200 g·mol⁻¹. -1 The PDI was 1.39, and the product yield was 96%.

[0117] Example 18

[0118] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the catalyst used is CCC-2EG, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 150,700 g·mol⁻¹. -1 The PDI was 1.26, and the product yield was 89%.

[0119] Example 19

[0120] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the final polymerization temperature is 250°C, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 163,200 g·mol⁻¹. -1 The PDI was 1.42, and the product yield was 94%.

[0121] Example 20

[0122] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the final polymerization temperature is 260°C, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 132,400 g·mol⁻¹. -1 The PDI was 1.73, and the product yield was 96%.

[0123] Example 21

[0124] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the transesterification temperature is 100°C, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 118,400 g·mol⁻¹. -1The PDI was 1.60, and the product yield was 92%.

[0125] Example 22

[0126] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the transesterification temperature is 140°C, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 126,500 g·mol⁻¹. -1 The PDI was 1.62, and the product yield was 95%.

[0127] Example 23

[0128] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the transesterification temperature is 160°C, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 131,800 g·mol⁻¹. -1 The PDI was 1.65, and the product yield was 93%.

[0129] Example 24

[0130] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the transesterification temperature is 180°C, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 125,100 g·mol⁻¹. -1 The PDI was 1.63, and the product yield was 97%.

[0131] Example 25

[0132] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent catalyst. The difference from Example 1 is that the molar ratio of ChCl to EG in the quaternary ammonium eutectic solvent catalyst is changed to 1:1, while all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 139,300 g·mol⁻¹. -1 The PDI was 1.57, and the product yield was 96%.

[0133] Example 26

[0134] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the diol monomer used is 1,4-butanediol; all other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 146,900 g·mol⁻¹. -1 The PDI was 1.77, and the product yield was 92%.

[0135] Example 27

[0136] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the diol monomer used is 1,2-pentanediol, while the other conditions remain the same. The synthesized isosorbide-type polycarbonate has a weight-average molecular weight of 127,600 g·mol⁻¹. -1 The PDI was 1.48, and the product yield was 89%.

[0137] Example 28

[0138] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the carbonate monomer used is dimethyl carbonate, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 117,900 g·mol⁻¹. -1 The PDI was 1.58, and the product yield was 95%.

[0139] Example 29

[0140] This embodiment presents a method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst. The difference from Example 1 is that the diester monomer used is diethyl carbonate, while the other conditions remain the same. The synthesized isosorbide-based polycarbonate has a weight-average molecular weight of 104,800 g·mol⁻¹. -1 The PDI was 1.55, and the product yield was 94%.

[0141] Comparative Example 1

[0142] Ester exchange stage: Under normal pressure and nitrogen atmosphere, 0.05 mol (7.35 g) isosorbide and 0.05 mol (10.70 g) diphenyl carbonate were added to the reactor, and the temperature was raised to 130 °C. After the raw materials were completely melted, 1.87 × 10⁻⁶ mol of the ionic liquid bis-(3-methyl-1-imidazolium)-ethylene dichloro[C₂(Min)₂][Br]₂ was added. -4 g (molar amount of isosorbide 1.5 × 10⁻⁶) -5 The reaction proceeded for 3 hours; during the polycondensation stage, the temperature was gradually increased to 240℃, and the pressure was gradually decreased to a vacuum (130 Pa), with the reaction lasting 20 minutes. The final isosorbide-based polycarbonate obtained had a weight-average molecular weight of 89800 g·mol⁻¹. -1 The yield was 99%.

[0143] Comparative Example 2

[0144] Transesterification stage: Under normal pressure and nitrogen atmosphere, 0.05 mol (7.35 g) isosorbide and 0.05 mol (10.70 g) diphenyl carbonate were added to the reactor, and the temperature was raised to 140 °C. After the raw materials were completely melted, 3.58 × 10⁻⁶ mol of the eutectic solvent 1-hydroxyethyl-3-methylimidazolium chloride-2-ethylene glycol was added. -4g (2.5 × 10⁻⁶ g of isosorbide) -5 The reaction proceeded for 2 hours; during the polycondensation stage, the temperature was gradually increased to 240℃, and the pressure was gradually decreased to vacuum (<1 kPa), with the reaction lasting 15 minutes. The final isosorbide-based polycarbonate obtained had a weight-average molecular weight of 102,000 g·mol⁻¹. -1 The yield was 99%.

[0145] By comparing Examples 1-2 with Example 1, it can be seen that although the bio-based polycarbonate prepared without using the quaternary ammonium eutectic solvent used in this invention has a higher yield, the amount of catalyst used is large and the molecular weight of the product is low, which does not achieve the technical effect of this invention.

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing polycarbonate using a quaternary ammonium eutectic solvent as a catalyst, characterized in that, The steps are as follows: After mixing the glycol monomer and the diester carbonate monomer, the mixture is heated under a nitrogen atmosphere until the substrate melts. Then, a quaternary ammonium eutectic solvent is added, and after transesterification, pre-condensation and final condensation reactions, polycarbonate is obtained. The quaternary ammonium eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, wherein the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (0.1-10):1; the hydrogen bond acceptor is selected from any one of the following structures:

2. The method according to claim 1, characterized in that, The hydrogen bond acceptor is selected from any of the following structures:

3. The method according to claim 1, characterized in that, The hydrogen bond donor is selected from any of the following structures:

4. The method according to claim 3, characterized in that, The diol monomer is any one of the following compounds: 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, isosorbide, isomannitol, isoidutol, 4,4'-dihydroxydiphenylmethane, 4,4'-cyclohexylbisphenol, and 4,4'-isopropylidene biphenol.

5. The method according to claim 4, characterized in that, The carbonate monomer is any one of dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and diphenyl carbonate.

6. The method according to claim 5, characterized in that, The molar ratio of the diol monomer, diphenyl carbonate monomer, and quaternary ammonium eutectic solvent is 1:(1-1.5):(1×10⁻⁶). -5 -1×10 -3 ).

7. The method according to claim 6, characterized in that, The transesterification reaction temperature is 100-200℃, the reaction time is 10min-2h, and the reaction pressure is atmospheric pressure.

8. The method according to claim 7, characterized in that, The prepolymerization reaction temperature is 220-280℃, the reaction time is 30min-3h, and the absolute reaction pressure is 20-80Pa.

9. The method according to claim 8, characterized in that, The final polycondensation reaction temperature is 220-280℃, the reaction time is 30min-3h, and the absolute reaction pressure is 50-1000Pa.

10. The polycarbonate prepared by the method according to any one of claims 1-9, characterized in that, The weight-average molecular weight of the polycarbonate can be as high as 155,100-197,600 g·mol⁻¹. -1 .

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