A process for the preparation of a bisphenol fluorene polyether

Abstract

The application provides a preparation method of a diphenylfluorene polyether. The method uses diphenylfluorene as a substrate, butylene oxide as an epoxide monomer, toluene as an organic solvent, and under the action of a composite catalyst, reacts at 110-200 DEG C for 2-6 hours to obtain the diphenylfluorene polyether. The composite catalyst is obtained by reacting a porous aromatic skeleton with a bromoalkyl quaternary ammonium salt to obtain a quaternary ammonium salt functionalized porous aromatic skeleton, and finally, a basic catalyst is limitedly encapsulated in the pore channel of the quaternary ammonium salt functionalized porous aromatic skeleton by electrostatic attraction. The catalyst of the method can be recycled and reused, and the yield retention rate is greater than or equal to 92% after the composite catalyst is used for 5 cycles, and the method is suitable for optical display, high-frequency circuit board, semiconductor packaging and other fields.

Description

Technical Field

[0001] This invention relates to the field of bisphenol fluorene polyether synthesis technology, and specifically to a method for preparing bisphenol fluorene polyether. Background Technology

[0002] Bisphenol fluorene polyethers are a class of high-performance polyether materials prepared by anionic ring-opening polymerization of bisphenol fluorene (9,9-bis[(4-yl)phenyl]fluorene) with epoxide butane as an initiator. While traditional bisphenol A type polyether resins have excellent overall performance and mature processing capabilities, and are widely used in electronics, optics, and insulation, they suffer from drawbacks such as low glass transition temperature, poor high-temperature creep resistance, insufficient dimensional stability, high optical birefringence, and poor solubility, making it difficult to meet the stringent requirements of emerging industries such as high-precision electronics, high-definition optics, and high-temperature semiconductors.

[0003] To address the aforementioned shortcomings, the industry has adopted bisphenol A-based polyethers with rigid fluorene rings and oxybutyl groups as substitutes for bisphenol A in the preparation of polyether polymers. The unique non-planar spatial structure of the fluorene group and the rigid structure of the oxybutyl group can disrupt the tight packing of molecular chains, significantly improving the material's heat resistance, refractive index, and dimensional stability, reducing birefringence, and simultaneously improving solubility, enabling solution processing and broadening application scenarios. This type of material was initially developed abroad, but its industrialization was initially hampered by low production capacity and high costs of high-purity monomers. With the mass production of high-purity bisphenol fluorene in China, bisphenol fluorene polyethers have experienced rapid development, possessing advantages such as high heat resistance, low dielectric constant, high transparency, and low stress. Currently, this material is applied in high-end fields such as optical displays, high-frequency circuit boards, semiconductor packaging, and new energy film materials. However, challenges remain, including the difficulty in achieving a balance between toughness and rigidity, high barriers to entry in high-end grade preparation, and a limited number of specialized grades. Therefore, it remains a key research direction for high-performance polymer materials.

[0004] Currently, the industrial production of bisphenol fluorene polyethers mainly employs homogeneous anionic ring-opening polymerization using alkaline catalysts such as potassium hydroxide (KOH) and sodium hydroxide (NaOH). While this process is inexpensive and simple to operate, it has significant drawbacks: First, the homogeneous catalyst is completely dissolved in the reaction system and cannot be separated and recovered after the reaction, resulting in catalyst waste, increased product purification costs, and metal ion residues. Second, the active chain ends are extremely sensitive to trace amounts of water, oxygen, and other impurities, leading to frequent chain transfer and chain termination reactions, resulting in a wide molecular weight distribution (PDI typically greater than 1.8) and poor batch-to-batch consistency. Third, for epoxides with significant steric hindrance, such as epoxides, homogeneous catalysis results in slow ring-opening rates, incomplete conversion, and insufficient controllability of the polymerization process, making it difficult to accurately synthesize block or regular polyether structures. To address these issues, researchers have attempted to use porous materials (such as mesoporous silica, metal-organic frameworks, and covalent organic frameworks) to support alkaline catalysts, thereby achieving heterogeneous catalysis and catalyst recovery. However, existing supports suffer from insufficient stability in strongly alkaline reaction environments, or their preparation processes are complex and costly, and their encapsulation efficiency and ability to control polymerization behavior still need improvement. Therefore, developing a method for preparing bisphenol fluorene polyethers with recyclable catalysts, controllable polymerization processes, narrow molecular weight distribution of products, and higher heat resistance has significant industrial value and market prospects.

[0005] Polyether polymers, with their main chains containing numerous ether bonds, possess excellent resistance to high and low temperatures, hydrolysis, chemical corrosion, electrical insulation, and mechanical properties. They are also easy to mold and process, making them one of the most widely used systems in specialty engineering plastics, resin matrices, and electronic insulating materials. While conventional polyether materials offer mature processes and high cost-effectiveness, they generally suffer from limited heat resistance, susceptibility to high-temperature creep, low heat distortion temperature, mediocre optical properties, and dielectric properties that cannot meet the demands of high-frequency, high-speed electronics, thus limiting their use in high-end semiconductors, precision optics, high-temperature environments, and high-frequency communications. With the rapid development of the electronics, information technology, new energy, aerospace, and high-end optics industries, the market demands materials with higher heat resistance, lower dielectric loss, higher transparency, lower internal stress, and better dimensional stability. Traditional general-purpose polyethers are no longer suitable for demanding high-end operating environments; therefore, developing modified polyether materials with high heat resistance, low dielectric loss, high light transmittance, and structural stability has become a key research direction in the industry. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing bisphenol fluorene polyether. This method is green, environmentally friendly, efficient, and the composite catalyst is recyclable. It can solve the problems of difficult catalyst separation and recovery and easy loss of active components that are common in the preparation of existing polyether materials.

[0007] One objective of this invention is to provide a method for preparing bisphenol fluorene polyether. The method involves adding bisphenol fluorene, a composite catalyst, and an inert organic solvent to a reaction vessel, subjecting the reaction to vacuum deoxygenation and dehydration, and then heating the vessel to 80–120°C for 1–2 hours of pre-activation. After pre-activation, the temperature is raised to 110–200°C, and at least one epoxide monomer is added to the reaction vessel for polymerization for 2–6 hours. After the reaction, the vessel is cooled and degassed to obtain the bisphenol fluorene polyether product.

[0008] The preparation process of the composite catalyst includes the following steps: (1) Under the protection of nitrogen, rigid aromatic monomers and anhydrous aluminum chloride are dissolved in anhydrous chloroform and stirred at 50-80°C for 24-72 hours. After the reaction is completed, the mixture is washed with methanol and dilute hydrochloric acid in sequence and dried under vacuum at 80-120°C for 12-24 hours to obtain a porous aromatic skeleton. (2) The porous aromatic framework was dispersed in anhydrous N,N-dimethylformamide, and a brominated alkyl quaternary ammonium salt was added. Under inert gas protection, the mixture was stirred at 80-120°C for 24-48 hours. After the reaction was completed, the mixture was centrifuged and washed successively with N,N-dimethylformamide and methanol. The mixture was then dried under vacuum at 50-80°C for 12-24 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework. (3) Disperse the quaternary ammonium salt functionalized porous aromatic framework in a polar solvent and add an alkaline catalyst; stir at 20-60℃ for 4-12 hours under inert gas protection; after the reaction is completed, centrifuge and wash 2-4 times with a polar solvent, and vacuum dry at 40-60℃ for 6-12 hours to obtain the composite catalyst.

[0009] Furthermore, in step (1) of the preparation of the composite catalyst, the molar ratio of the rigid aromatic monomer to anhydrous aluminum chloride is 1:(2-10), wherein the rigid aromatic monomer is selected from at least one of p-terphenyl, tetraphenylmethane, tetra(4-bromophenyl)methane or tetra(4-ynylphenyl)methane.

[0010] Further, in the preparation step (2) of the composite catalyst, the bromoalkyl quaternary ammonium salt is one of (3-bromopropyl)trimethylammonium bromide, (4-bromobutyl)trimethylammonium bromide or (6-bromohexyl)trimethylammonium bromide, and the mass ratio of the bromoalkyl quaternary ammonium salt to the porous aromatic skeleton is (1-5):1.

[0011] Further, in the preparation step (3) of the composite catalyst, the polar solvent is selected from methanol, ethanol, acetonitrile or tetrahydrofuran, and the mass ratio of the quaternary ammonium salt functionalized porous aromatic framework to the polar solvent is 1: (20-100); the alkaline catalyst is potassium hydroxide, sodium hydroxide, sodium methoxide (potassium) or sodium ethoxide (potassium), and the mass ratio of the alkaline catalyst to the quaternary ammonium salt functionalized porous aromatic framework is 1: (2-10).

[0012] Furthermore, the inert organic solvent is selected from toluene, cyclohexane, acetonitrile, dioxane, or dimethyl sulfoxide, and the mass ratio of the inert organic solvent to bisphenol fluorene is (1.5–3):1.

[0013] Furthermore, the epoxide monomer is selected from one or more of ethylene oxide, propylene oxide, and butane oxide.

[0014] Furthermore, the molar ratio of epoxide monomer to bisphenol fluorene is (2-150):1.

[0015] Furthermore, the mass ratio of bisphenol fluorene to the alkaline catalyst supported in the composite catalyst is 100:(0.5-3).

[0016] Further, after cooling the reaction mixture, the composite catalyst solid is separated by centrifugation (centrifugation speed 8000-10000 rpm, time 5-10 minutes) or by vacuum filtration using a polytetrafluoroethylene or polypropylene filter membrane with a pore size of 0.22-0.45 μm. The solid is then washed with anhydrous methanol or toluene, vacuum dried, and directly recycled.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a quaternary ammonium salt-functionalized porous aromatic framework to encapsulate an alkaline catalyst, thus preparing a heterogeneous composite catalyst. This composite catalyst is insoluble in the reaction solvent and can be recovered from the reaction mixture after polymerization by simple centrifugation or filtration. After washing and drying, it can be directly used in the next batch of polymerization. This significantly reduces the consumption of alkaline catalyst and the difficulty of product purification, aligning with the development direction of green chemistry. In contrast, traditional homogeneous alkaline catalytic systems have catalysts that are completely dissolved in the reaction system and cannot be recovered. Each batch requires the addition of catalyst, resulting in high production costs and complex purification processes.

[0018] Utilizing the nano-confinence effect of porous aromatic framework channels and the influence of quaternary ammonium groups on OH - The electrostatic anchoring effect confines the active centers of the polymerization reaction within the nanopores, effectively suppressing chain transfer and chain termination reactions, making the polymerization process closer to living polymerization. This results in high batch-to-batch quality consistency, low impurity content, and good processing stability, making it particularly suitable for high-end optical films, high-frequency circuit boards, and other fields with stringent requirements for material uniformity.

[0019] This invention uses epoxide as a monomer and leverages its long-chain rigid structure and the synergistic effect of the fluorene ring, combined with the regularization effect of confined catalysis on the chain structure, to prepare a bisphenol fluorene polyether with a high glass transition temperature. This meets the requirements for use in high-temperature semiconductor packaging, automotive electronics, and other high-temperature applications.

[0020] This invention enables the preparation of well-structured block polyethers by adding different epoxy monomers in stages, and the preparation of uniformly composed random polyethers by mixing and adding different monomers. The confinement effect of the porous aromatic framework protects the active chain ends during stepwise polymerization, avoiding chain deactivation and side reactions during stage switching, and significantly improving the purity of the blocks. This feature allows the invention to flexibly customize the chain structure of the polyether according to application requirements, thus broadening the application scenarios of the product.

[0021] The composite catalyst of this invention is prepared using conventional chemical unit operations, requiring no special equipment and easily scalable for production. The rigid aromatic monomers used (such as p-terphenyl, tetraphenylmethane, and tetra(4-bromophenyl)methane), quaternary ammonium salts (bromoalkyltrimethylammonium bromide), and basic catalysts (potassium hydroxide, sodium hydroxide, sodium methoxide, potassium methoxide, and sodium ethoxide) are all commercially available raw materials or can be synthesized using known methods, resulting in a wide range of raw material sources and controllable costs. Furthermore, this method is applicable not only to butane oxide but also to ethylene oxide, propylene oxide, and their mixtures, demonstrating good versatility.

[0022] This invention avoids the contamination of products by catalyst residues in traditional homogeneous catalytic systems. The recovered composite catalyst can be recycled multiple times, reducing the generation of chemical waste. The polymerization reaction is carried out in inert solvents such as toluene, which can be recycled and reused, making the overall process environmentally friendly. Attached Figure Description

[0023] Figure 1 This is a structural diagram of bisphenol fluorene polyether.

[0024] Figure 2 This is a scanning electron microscope image of the composite catalyst. Detailed Implementation

[0025] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are based on conventional conditions or product instructions. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0026] Example 1 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 24 g of composite catalyst (approximately 3.5 g based on potassium hydroxide active ingredient), and 438 g of toluene are added to a reactor. Vacuum is maintained for 30 minutes, then nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is pre-activated at 100℃ for 1.5 hours. Subsequently, the temperature is raised to 150℃, and 720 g of epoxide is slowly and continuously added to the reactor, controlling the feeding rate to maintain the reaction temperature at 150±5℃, and the reaction is carried out for 4 hours. The temperature is then lowered to 60℃, and vacuum degassing is performed for 10 minutes. The bisphenol fluorene polyether is then discharged. The structural formula of the bisphenol fluorene polyether is as follows. Figure 1 As shown. Preparation of composite catalysts: (1) Under nitrogen protection, 0.1 mol of p-terphenyl and 0.6 mol of anhydrous aluminum chloride were dissolved in 200 mL of anhydrous chloroform. The mixture was stirred at 65 °C for 48 hours. After the reaction was completed, the solid was separated by centrifugation at 9000 rpm for 8 minutes. The precipitate was washed twice with methanol and once with 1 M dilute hydrochloric acid. After each washing, the precipitate was centrifuged and dried under vacuum at 100 °C for 18 hours to obtain a porous aromatic framework.

[0027] (2) 1.0 g of porous aromatic framework was dispersed in 30 mL of anhydrous N,N-dimethylformamide, and 3.0 g of (3-bromopropyl)trimethylammonium bromide was added. The mixture was stirred at 100 °C for 36 hours under nitrogen protection. After the reaction was completed, the solid was separated by centrifugation at 9500 rpm for 10 minutes. The solid was washed twice with N,N-dimethylformamide and three times with methanol, and centrifuged after each wash. The solid was dried under vacuum at 65 °C for 18 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework.

[0028] (3) 1.0 g of quaternary ammonium salt-functionalized porous aromatic framework was dispersed in 60 mL of methanol, and 0.17 g of potassium hydroxide was added. The mixture was stirred at 40 °C for 8 hours under nitrogen protection. After the reaction was complete, the solid was separated by centrifugation at 8000 rpm for 6 minutes, washed three times with methanol, and centrifuged again after each wash. The solid was then vacuum dried at 50 °C for 9 hours to obtain the composite catalyst. Figure 2 This is a scanning electron microscope image of the composite catalyst.

[0029] Example 2 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 2.7 g of composite catalyst (approximately 0.9 g based on sodium hydroxide active ingredient), and 263 g of toluene are added to a reactor. Vacuum is maintained for 30 minutes, nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is then pre-activated at 80°C for 1.5 hours. Subsequently, the temperature is raised to 110°C, and 72 g of epoxide is slowly and continuously added to the reactor, controlling the feeding rate to maintain the reaction temperature at 110±5°C, and the reaction is carried out for 2 hours. The temperature is then lowered to 60°C, and vacuum degassing is performed for 10 minutes, yielding the bisphenol fluorene polyether.

[0030] Preparation of composite catalysts: (1) Under nitrogen protection, 0.1 mol of p-terphenyl and 0.2 mol of anhydrous aluminum chloride were dissolved in 200 mL of anhydrous chloroform. The mixture was stirred at 50 °C for 24 hours. After the reaction was completed, the solid was separated by centrifugation at 8000 rpm for 5 minutes. The precipitate was washed twice with methanol and once with 1 M dilute hydrochloric acid. After each washing, the precipitate was centrifuged and dried under vacuum at 80 °C for 12 hours to obtain a porous aromatic framework.

[0031] (2) 1.0 g of porous aromatic framework was dispersed in 30 mL of anhydrous N,N-dimethylformamide, and 1.0 g of (3-bromopropyl)trimethylammonium bromide was added. The mixture was stirred at 80 °C for 24 hours under nitrogen protection. After the reaction was completed, the solid was separated by centrifugation at 9000 rpm for 8 minutes. The solid was washed twice with N,N-dimethylformamide and three times with methanol, and centrifuged after each wash. The solid was dried under vacuum at 50 °C for 12 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework.

[0032] (3) Disperse 1.0 g of quaternary ammonium salt-functionalized porous aromatic framework in 30 mL of methanol and add 0.5 g of sodium hydroxide. Stir at 20 °C for 4 hours under nitrogen protection. After the reaction is complete, centrifuge at 8000 rpm for 5 minutes to separate the solid, wash twice with methanol, and centrifuge after each wash. Dry under vacuum at 40 °C for 6 hours to obtain the composite catalyst.

[0033] Example 3 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 58.3 g of composite catalyst (approximately 5.3 g based on sodium methoxide as active ingredient), and 525 g of toluene are added to a reactor. Vacuum is maintained for 30 minutes, then nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is then pre-activated at 120°C for 1.5 hours. Subsequently, the temperature is raised to 200°C, and 1380 g of epoxide butane is slowly and continuously added to the reactor, controlling the feeding rate to maintain the reaction temperature at 200±5°C, and the reaction is carried out for 6 hours. The temperature is then lowered to 60°C, and vacuum degassing is performed for 10 minutes, yielding the bisphenol fluorene polyether.

[0034] Preparation of composite catalysts: (1) Under nitrogen protection, 0.1 mol of p-terphenyl and 1.0 mol of anhydrous aluminum chloride were dissolved in 200 mL of anhydrous chloroform. The mixture was stirred at 80 °C for 72 hours. After the reaction was completed, the solid was separated by centrifugation at 10,000 rpm for 10 minutes, and the supernatant was discarded. The precipitate was washed twice with methanol and once with 1 M dilute hydrochloric acid. After each washing, the precipitate was centrifuged and dried under vacuum at 120 °C for 24 hours to obtain a porous aromatic framework.

[0035] (2) 1.0 g of porous aromatic framework was dispersed in 30 mL of anhydrous N,N-dimethylformamide, and 5.0 g of (3-bromopropyl)trimethylammonium bromide was added. The mixture was stirred at 120 °C for 48 hours under nitrogen protection. After the reaction was completed, the solid was separated by centrifugation at 10,000 rpm for 12 minutes. The solid was washed twice with N,N-dimethylformamide and three times with methanol, and centrifuged after each washing. The solid was dried under vacuum at 80 °C for 24 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework.

[0036] (3) Disperse 1.0 g of quaternary ammonium salt-functionalized porous aromatic framework in 100 mL of methanol and add 0.1 g of sodium methoxide. Stir at 60 °C for 12 hours under nitrogen protection. After the reaction is complete, centrifuge at 8000 rpm for 8 minutes to separate the solid, wash with methanol 4 times, and centrifuge after each wash. Dry under vacuum at 60 °C for 12 hours to obtain the composite catalyst.

[0037] Example 4 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 13 g of composite catalyst (approximately 2.6 g based on potassium methoxide as the active ingredient), and 350 g of toluene are added to a reactor. Vacuum is maintained for 30 minutes, then nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is then pre-activated at 90°C for 1.5 hours. Subsequently, the temperature is raised to 130°C, and 360 g of epoxide is slowly and continuously added to the reactor, controlling the feeding rate to maintain the reaction temperature at 130±5°C, and the reaction is carried out for 3 hours. The temperature is then lowered to 60°C, and vacuum degassing is performed for 10 minutes, yielding the bisphenol fluorene polyether.

[0038] Preparation of composite catalysts: (1) Under nitrogen protection, 0.1 mol tetraphenylmethane and 0.4 mol anhydrous aluminum chloride were dissolved in 200 mL anhydrous chloroform. The mixture was stirred at 60 °C for 36 hours. After the reaction was completed, the solid was separated by centrifugation at 8500 rpm for 7 minutes, and the supernatant was discarded. The precipitate was washed twice with methanol and once with 1 M dilute hydrochloric acid. After each washing, the precipitate was centrifuged and dried under vacuum at 90 °C for 15 hours to obtain a porous aromatic framework.

[0039] (2) 1.0 g of porous aromatic framework was dispersed in 30 mL of anhydrous N,N-dimethylformamide, and 2.0 g of (4-bromobutyl)trimethylammonium bromide was added. The mixture was stirred at 90 °C for 30 hours under nitrogen protection. After the reaction was completed, the solid was separated by centrifugation at 9200 rpm for 9 minutes. The solid was washed twice with N,N-dimethylformamide and three times with methanol, and centrifuged after each wash. The solid was dried under vacuum at 60 °C for 15 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework.

[0040] (3) Disperse 1.0 g of quaternary ammonium salt-functionalized porous aromatic framework in 40 mL of ethanol and add 0.25 g of potassium methoxide. Stir at 30 °C for 6 hours under nitrogen protection. After the reaction is complete, centrifuge at 6500 rpm for 7 minutes to separate the solid, wash with ethanol 3 times, and centrifuge after each wash. Dry under vacuum at 45 °C for 8 hours to obtain the composite catalyst.

[0041] Example 5 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 38.3 g of composite catalyst (approximately 4.4 g based on sodium ethoxide active ingredient), and 480 g of toluene are added to a reactor. Vacuum is maintained for 30 minutes, then nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is then pre-activated at 110°C for 1.5 hours. Subsequently, the temperature is raised to 170°C, and 1000 g of epoxide butane is slowly and continuously added to the reactor, controlling the feeding rate to maintain the reaction temperature at 170±5°C, and the reaction is carried out for 5 hours. The temperature is then lowered to 60°C, and vacuum degassing is performed for 10 minutes, yielding the bisphenol fluorene polyether.

[0042] Preparation of composite catalysts: (1) Under nitrogen protection, 0.1 mol of tetrakis(4-bromophenyl)methane and 0.8 mol of anhydrous aluminum chloride were dissolved in 200 mL of anhydrous chloroform. The mixture was stirred at 70 °C for 60 hours. After the reaction was completed, the solid was separated by centrifugation at 9500 rpm for 9 minutes, and the supernatant was discarded. The precipitate was washed twice with methanol and once with 1 M dilute hydrochloric acid. After each washing, the precipitate was centrifuged and dried under vacuum at 110 °C for 20 hours to obtain a porous aromatic framework.

[0043] (2) 1.0 g of porous aromatic framework was dispersed in 30 mL of anhydrous N,N-dimethylformamide, and 4.0 g of (6-bromohexyl)trimethylammonium bromide was added. The mixture was stirred at 110 °C for 40 hours under nitrogen protection. After the reaction was completed, the solid was separated by centrifugation at 9800 rpm for 11 minutes. The solid was washed twice with N,N-dimethylformamide and three times with methanol, and centrifuged after each washing. The solid was dried under vacuum at 70 °C for 20 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework.

[0044] (3) 1.0 g of quaternary ammonium salt-functionalized porous aromatic framework was dispersed in 80 mL of acetonitrile, and 0.13 g of sodium ethoxide was added. The mixture was stirred at 50 °C for 10 hours under nitrogen protection. After the reaction was completed, the solid was separated by centrifugation at 7500 rpm for 8 minutes, washed three times with acetonitrile, and centrifuged after each wash. The solid was then dried under vacuum at 55 °C for 10 hours to obtain the composite catalyst.

[0045] Comparative Example 1 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 3.5 g of potassium hydroxide, and 438 g of toluene are added to a reaction vessel. Vacuum is maintained for 30 minutes, then nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is then pre-activated at 100℃ for 1.5 hours. Subsequently, the temperature is raised to 150℃, and 720 g of epoxide is slowly and continuously added to the reaction vessel, controlling the feeding rate to maintain the reaction temperature at 150±5℃, and the reaction is carried out for 4 hours. The temperature is then lowered to 60℃, and vacuum degassing is performed for 10 minutes, yielding the bisphenol fluorene polyether.

[0046] Comparative Example 2 A method for preparing bisphenol fluorene polyether, the specific process is as follows: 175 g of bisphenol fluorene, 3.0 g of (3-bromopropyl)trimethylammonium bromide, 3.5 g of potassium hydroxide, and 438 g of toluene are added to a reaction vessel. Vacuum is maintained for 30 minutes, then nitrogen is introduced to restore atmospheric pressure, and this process is repeated three times. The mixture is then pre-activated at 100℃ for 1.5 hours. Subsequently, the temperature is raised to 150℃, and 720 g of epoxide is slowly and continuously added to the reaction vessel, controlling the feeding rate to maintain the reaction temperature at 150±5℃, and the reaction is carried out for 4 hours. The temperature is then lowered to 60℃, and vacuum degassing is performed for 10 minutes, yielding the bisphenol fluorene polyether.

[0047] Test case The polymerization yields of the products obtained in Examples 1-5 and Comparative Examples 1-2 were determined, and the stability of the composite catalysts in Examples 1-5 was tested for repeated use.

[0048] 1. Determination of polymerization yield: The polymerization yield was determined by gravimetric analysis. After the polymerization reaction was completed, the reaction mixture was cooled, degassed under vacuum to remove unreacted monomers and solvents, and the crude product was collected, dried under vacuum at 60°C to constant weight, and then weighed. The yield was calculated using the following formula: Yield (%) = (actual polymer mass / theoretical polymer mass calculated based on complete conversion of bisphenol fluorene) × 100%; the results are summarized in Table 1.

[0049] 2. The composite catalysts prepared in Examples 1-5 were reused 5 times. After each batch of polymerization, the reaction mixture was cooled to room temperature, and the composite catalyst was collected by centrifugation or filtration. It was washed 3 times with anhydrous methanol, dried under vacuum at 50°C for 9 hours, and then directly used in the next batch of polymerization. The yield after 5 uses was recorded. The stability of the composite catalyst after repeated use was examined according to the formula: Composite catalyst retention rate (%) = (Yield of the first polymerization reaction / Yield of the fifth polymerization reaction) × 100%. The results are shown in Table 2.

[0050] The polymerization yield results are shown in Table 1.

[0051] Table 1 Polymerization reaction yield The retention rates of the composite catalysts are shown in Table 2.

[0052] Table 2. Composite catalyst retention rate As can be seen from the data in Table 1, the polymerization yields of Examples 1-5 of this invention ranged from 86% to 94%, all higher than those of Comparative Example 1 (82%) and Comparative Example 2 (70%). This indicates that encapsulating the alkaline catalyst with a quaternary ammonium salt-functionalized porous aromatic framework can significantly improve the polymerization yield of bisphenol fluorene and epoxide. Example 2 had a yield of 89%, with a polymerization temperature of 110°C and a reaction time of 2 hours. The conditions were the mildest among all examples, resulting in insufficient monomer conversion and a relatively low yield, but still higher than the two comparative examples. Example 4 had a yield of 86%. Using tetraphenylmethane as the porous aromatic framework monomer resulted in greater steric hindrance, and the regularity and confinement effect of the porous aromatic framework pore structure were slightly weaker than those of the terphenyl system, leading to a slightly lower yield than the other examples. Example 5 achieved a yield of 90%, using tetra(4-bromophenyl)methane as the porous aromatic framework monomer and grafting a C6 long-chain quaternary ammonium salt ((6-bromohexyl)trimethylammonium bromide). The longer graft chain may have slightly affected the enrichment efficiency of the pores for the substrate, resulting in a moderate yield. Example 1 achieved a yield of 92%, using p-terphenyl as the monomer, grafting a C3 short-chain quaternary ammonium salt ((3-bromopropyl)trimethylammonium bromide), and a polymerization temperature of 150°C. The parameters were well-matched, resulting in a high yield. Example 3 achieved a yield of 94%: the highest polymerization temperature (200°C) and the longest reaction time (6 hours) resulted in the most complete conversion. Simultaneously, the stronger basicity of sodium methoxide led to higher initiation efficiency, achieving the highest yield of 94%.

[0053] Comparative Example 1 achieved a yield of 82%, employing a traditional homogeneous base catalytic system. In this system, the base was completely dissolved, and the active chain ends were directly exposed to the reaction medium, making it sensitive to trace impurities and prone to chain transfer or termination. Furthermore, the steric hindrance of butane oxide and its slow ring-opening rate led to incomplete polymerization and the low yield. Comparative Example 2 achieved a yield of only 70%, using a catalytic system with a physical mixture of quaternary ammonium salt and base, but without a porous aromatic framework support. Due to the lack of confining and anchoring effects from the porous aromatic framework, the quaternary ammonium salt and base could not form a stable confined catalytic environment, resulting in dispersed and easily deactivated active centers. Simultaneously, the base remained homogeneous in the reaction system, leading to the lowest yield among all tested groups. This comparative example further demonstrates that quaternary ammonium salts alone cannot achieve effective confined catalysis, and that a porous aromatic framework support is the structural basis for achieving highly efficient catalysis.

[0054] Table 2 shows the yield retention rate (i.e., the percentage of the fifth yield to the first yield) of the composite catalysts in Examples 1-5 after 5 cycles. The retention rate of all examples is above 92%, indicating that the composite catalysts prepared by this invention have excellent reusability. Example 2 has a retention rate of 92%. Due to the lower initial yield and the relatively greater impact of physical catalyst loss in each cycle, the yield decrease was slightly higher than in other examples. Example 4 has a retention rate of 94%. The pore regularity of the tetraphenylmethane porous aromatic framework is slightly weaker, and slight catalyst loss may occur during cycling, resulting in a moderate retention rate. Example 5 has a retention rate of 94%. The C6 long-chain quaternary ammonium salt may undergo slight structural rearrangement during cycling due to its greater chain flexibility, resulting in slightly lower encapsulation stability of the basic catalyst compared to the C3 short-chain system, with a retention rate comparable to Example 4. Example 3 achieved a retention rate of 96%. Although it had the highest polymerization temperature (200°C), the amount of sodium methoxide was low (the mass ratio of quaternary ammonium salt functionalized porous aromatic framework to sodium methoxide was 10:1), resulting in minimal loss of active centers during recycling and a high retention rate. Example 1 achieved the highest retention rate (97%). It employed a moderate polymerization temperature of 150°C, C3 short-chain quaternary ammonium salt grafting, and a mild encapsulation condition of 40°C, achieving an optimal balance of parameters. The carbon-carbon bond framework of the porous aromatic framework was highly stable under the reaction conditions, and the electrostatic interaction between the quaternary ammonium groups and the basic catalyst remained good during recycling. No significant degradation of the catalyst structure was observed after 5 cycles, thus resulting in the highest retention rate.

[0055] As can be seen from the data in Table 2, the yield retention rate of the composite catalysts in all embodiments was ≥92% after 5 cycles, proving that the composite catalysts prepared in this invention have excellent reusability. Among them, Example 1, which uses p-terphenyl as a porous aromatic skeleton monomer, grafts C3 short-chain quaternary ammonium salt, and has a polymerization temperature of 150°C, exhibits the best cycle stability (retention rate of 97%).

[0056] Comparative Examples 1 and 2 are not listed in Table 2 because: the catalyst in Comparative Example 1 (homogeneous alkaline catalyst) is completely dissolved in the reaction system and cannot be separated and recovered by centrifugation or filtration after the reaction, so there is no possibility of "recycling"; although a small amount of solid can be obtained by centrifugation in Comparative Example 2 (physical mixing of quaternary ammonium salt and alkaline catalyst), the content of alkaline catalyst in the solid is extremely low and cannot maintain effective catalytic activity, so the cycle test is not of practical significance.

[0057] There is no direct positive correlation between initial yield and retention rate: Example 3 had the highest initial yield (94%) and a retention rate of 96%; Example 1 had an initial yield of 92% but the highest retention rate (97%); Example 2 had an initial yield of 89% and a retention rate of 92%. A high initial yield does not necessarily mean a high retention rate; the retention rate depends more on the structural stability of the catalyst. Example 1 (polymerization at 150℃) had the highest retention rate; although Example 3 (high-temperature polymerization at 200℃) had the highest yield, the high temperature may have had a slight thermal effect on the porous aromatic framework and quaternary ammonium groups, resulting in a slightly lower retention rate than Example 1. The retention rates of all examples were ≥92%, proving that the composite catalyst had a reasonable structural design, the porous aromatic framework provided a stable physical support, and the electrostatic interaction between the quaternary ammonium groups and the basic catalyst remained good during recycling, achieving the "heterogeneity" and "recyclability" of the basic catalyst, and solving the industry problem of the inability to recover catalysts in homogeneous basic catalytic systems during traditional polyether production.

[0058] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing bisphenol fluorene polyether, characterized in that: Bisphenol fluorene, a composite catalyst, and an inert organic solvent are added to a reactor. The reactor is then evacuated to remove oxygen and water. The mixture is then heated to 80–120°C for 1–2 hours for pre-activation. After pre-activation, the temperature is raised to 110–200°C, and at least one epoxide monomer is added to the reactor. The polymerization reaction is carried out for 2–6 hours. After the reaction is completed, the mixture is cooled and degassed to obtain the bisphenol fluorene polyether product. The structural formula of the bisphenol fluorene polyether product is as follows: When a=0, b=0 and c≥1 in the structural formula, the structure is bisphenol fluorene polyether; when at least two of a, b, and c in the structural formula are greater than 1 and their order can be interchanged, the structure is bisphenol fluorene block polyether; when at least two of a, b, and c in the structural formula are greater than 1 and their order is random, the structure is bisphenol fluorene random polyether. The preparation process of the composite catalyst includes the following steps: (1) Under the protection of nitrogen, rigid aromatic monomers and anhydrous aluminum chloride are dissolved in anhydrous chloroform and stirred at 50-80°C for 24-72 hours. After the reaction is completed, the mixture is washed with methanol and dilute hydrochloric acid in sequence and dried under vacuum at 80-120°C for 12-24 hours to obtain a porous aromatic skeleton. (2) The porous aromatic framework was dispersed in anhydrous N,N-dimethylformamide, and a brominated alkyl quaternary ammonium salt was added. Under inert gas protection, the mixture was stirred at 80-120°C for 24-48 hours. After the reaction was completed, the mixture was centrifuged and washed successively with N,N-dimethylformamide and methanol. The mixture was then dried under vacuum at 50-80°C for 12-24 hours to obtain the quaternary ammonium salt functionalized porous aromatic framework. (3) Disperse the quaternary ammonium salt functionalized porous aromatic framework in a polar solvent and add an alkaline catalyst; stir at 20-60℃ for 4-12 hours under inert gas protection; after the reaction is completed, centrifuge and wash 2-4 times with a polar solvent, and vacuum dry at 40-60℃ for 6-12 hours to obtain the composite catalyst.

2. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that: In step (1) of the preparation of the composite catalyst, the molar ratio of the rigid aromatic monomer to anhydrous aluminum chloride is 1:(2-10), and the rigid aromatic monomer is selected from at least one of p-terphenyl, tetraphenylmethane, tetra(4-bromophenyl)methane or tetra(4-ynylphenyl)methane.

3. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that: In the preparation step (2) of the composite catalyst, the brominated alkyl quaternary ammonium salt is one of (3-bromopropyl)trimethylammonium bromide, (4-bromobutyl)trimethylammonium bromide or (6-bromohexyl)trimethylammonium bromide, and the mass ratio of the brominated alkyl quaternary ammonium salt to the porous aromatic skeleton is (1-5):

1.

4. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that: In the preparation step (3) of the composite catalyst, the polar solvent is selected from methanol, ethanol, acetonitrile or tetrahydrofuran, and the mass ratio of the quaternary ammonium salt functionalized porous aromatic framework to the polar solvent is 1: (20-100); the alkaline catalyst is potassium hydroxide, sodium hydroxide, sodium methoxide (potassium) or sodium ethoxide (potassium), and the mass ratio of the alkaline catalyst to the quaternary ammonium salt functionalized porous aromatic framework is 1: (2-10).

5. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that, The inert organic solvent is selected from toluene, cyclohexane, acetonitrile, dioxane, or dimethyl sulfoxide, and the mass ratio of the inert organic solvent to bisphenol fluorene is (1.5–3):

1.

6. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that, The epoxide monomer is selected from one or more of ethylene oxide, propylene oxide, and butane oxide.

7. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that, The molar ratio of the epoxide monomer to bisphenol fluorene is (2-150):

1.

8. The method for preparing bisphenol fluorene polyether according to claim 1, characterized in that, The mass ratio of bisphenol fluorene to the alkaline catalyst supported in the composite catalyst is 100:(0.5-3).

9. A method for preparing bisphenol fluorene polyether according to claim 1, characterized in that, After cooling the reaction mixture, the composite catalyst solid is separated by centrifugation (centrifugation speed 8000-10000 rpm, time 5-10 minutes) or by vacuum filtration using a polytetrafluoroethylene or polypropylene filter membrane with a pore size of 0.22-0.45 μm. The solid is then washed with anhydrous methanol or toluene, vacuum dried, and directly recycled.

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