Porphyrin-quaternary phosphonium salt difunctional synergistic super-crosslinked polymer catalyst and method for catalytically synthesizing carbon dioxide-based polyol by using porphyrin-quaternary phosphonium salt difunctional synergistic super-crosslinked polymer catalyst

Abstract

The invention discloses a porphyrin-quaternary phosphonium salt bifunctional synergistic super-crosslinked polymer catalyst, which is a three-dimensional super-crosslinked polymer skeleton constructed through Friedel-Crafts reaction under the catalysis of Lewis acid by taking metalloporphyrin and quaternary phosphonium salt as precursor monomers and taking a cross-linking agent as a cross-linking unit. And the metal center of the metalloporphyrin and the cation functional group of the quaternary phosphonium salt are distributed in the three-dimensional super-crosslinked polymer skeleton. The invention discloses a method for catalytically synthesizing carbon dioxide-based polyol, which comprises the following step: by taking a porphyrin-quaternary phosphonium salt bifunctional synergistic super-crosslinked polymer catalyst as a catalyst, carrying out copolymerization reaction on epoxide and carbon dioxide in the presence of a chain transfer agent to prepare the carbon dioxide-based polyol. The catalyst provided by the invention still has good catalytic stability and proton tolerance in the presence of various chain transfer agents, and is beneficial to preparation of carbon dioxide-based polyols with low to medium molecular weight and relatively high carbonic ester chain segment content.

Description

Technical Field

[0001] This invention belongs to the field of porous catalytic materials and carbon dioxide resource conversion and carbon dioxide-based polyol synthesis technology. Specifically, it relates to a porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst and its preparation method, as well as a method for catalyzing the copolymerization reaction of carbon dioxide and epoxide to prepare carbon dioxide-based polyols. Background Technology

[0002] The copolymerization of carbon dioxide and epoxides to prepare carbon dioxide-based polyols is an important pathway to convert greenhouse gases into renewable polyols. Compared with traditional polyether or polyester polyols, carbon dioxide-based polyols contain both carbonate and ether structures in their molecular chains, which can endow polyurethane materials with higher polarity and mechanical properties. However, to obtain products with low molecular weight (number average molecular weight of 500–3000 g / mol) and high carbonate segment content, it is often necessary to introduce a high amount of chain transfer agent, which places higher demands on the proton tolerance and structural stability of the catalyst.

[0003] While existing zinc-cobalt bimetallic cyanide (DMC) catalysts can achieve the copolymerization of carbon dioxide and epoxides to prepare carbon dioxide-based polyols, they require operation under high pressure (>3 MPa) and high temperature (>80°C). However, under high chain transfer agent conditions, they are prone to generating byproducts such as cyclic carbonates, making it difficult to achieve both low molecular weight and high carbonate content (Journal of PolymerScience, Part A: Polymer Chemistry, 2012, 50, 5177–5184). Homogeneous SalenCo catalyst systems have good proton tolerance, but they suffer from difficulties in recovery and are prone to residues in the product (Journal of the American Chemical Society, 2020, 142, 19150–19160). Porous materials such as molecular sieves, metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have good structural stability, but their activation ability is limited, making it difficult to achieve efficient CO2 intercalation reaction under high temperature, pressure and co-catalyst conditions (Chem. Soc. Rev.2025,54 (12), 5912–5960).

[0004] Hyper-crosslinked polymers (HCPs) are a class of porous organic polymers prepared based on Friedel-Crafts reactions. They have attracted attention due to their structural stability and ease of loading metal centers. However, relying solely on the inert channels provided by aromatic frameworks makes it difficult to maintain high CO2 intercalation efficiency under high chain transfer agent conditions. Therefore, it is necessary to develop a heterogeneous catalyst that synergistically introduces metalloporphyrin active centers and quaternary phosphine cationic functional groups into porous organic frameworks, and independently controls the degree of crosslinking and pore structure through external crosslinking agents. This would improve proton tolerance and carbonate segment induction efficiency, enabling the controllable synthesis of low molecular weight, high carbonate content, carbon dioxide-based polyols. How to prepare hyper-crosslinked polymers that meet the above requirements is a pressing technical problem in this field, possessing significant scientific and application value. Summary of the Invention

[0005] The purpose of this invention is to provide a porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst. The inventors introduced the functional precursor metalloporphyrin and quaternary phosphine salt synergistically into a porous framework and used an external crosslinking agent to adjust the degree of crosslinking and pore structure, thus obtaining a heterogeneous catalyst with both high active site density and high proton tolerance. As a catalyst, it can realize the copolymerization reaction of carbon dioxide and epoxide to prepare carbon dioxide-based polyols with low to medium molecular weight (number average molecular weight of 1000-3500 g / mol).

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst is constructed by a three-dimensional hypercrosslinked polymer framework using metalloporphyrin and quaternary phosphine salt as precursor monomers and a crosslinking agent as the crosslinking unit under Lewis acid catalysis via Friedel-Crafts reaction. The metal center of the metalloporphyrin and the cationic functional groups of the quaternary phosphine salt are synergistically introduced and distributed in the three-dimensional hypercrosslinked polymer framework.

[0008] Another object of the present invention is to provide a method for preparing the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst, comprising the following steps:

[0009] Step (1): Using metal porphyrin and quaternary phosphine salt as precursor monomers, under a nitrogen or inert gas atmosphere, metal porphyrin, quaternary phosphine salt, Lewis acid catalyst and crosslinking agent are dissolved in an organic solvent to carry out a pre-crosslinking reaction to obtain a preliminary crosslinking intermediate.

[0010] Step (2): Based on the preliminary crosslinking intermediate obtained in step (1), the reaction temperature is increased to allow the system to undergo a Friedel-Crafts type crosslinking reaction. After the reaction is completed, the product is washed with methanol and deionized water, extracted with methanol using Soxhlet extraction, and dried under vacuum to obtain the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst.

[0011] In step (1), the temperature of the pre-crosslinking reaction is 15-65 ℃, preferably 25-45 ℃; the time of the pre-crosslinking reaction is 1-10 h, preferably 2-6 h.

[0012] The metalloporphyrin is one of aluminum porphyrin, cobalt porphyrin, iron porphyrin, and magnesium porphyrin.

[0013] The aluminum porphyrin is 5,10,15,20-tetraphenylporphyrin aluminum chloride (CAS No.: 71102-37-9); the cobalt porphyrin is 5,10,15,20-tetraphenylporphyrin cobalt (CAS No.: 14172-90-8); the iron porphyrin is 5,10,15,20-tetraphenylporphyrin iron (CAS No.: 16591-56-3); and the magnesium porphyrin is 5,10,15,20-tetraphenylporphyrin magnesium (CAS No.: 14640-21-2).

[0014] Preferably, the metalloporphyrin is aluminum porphyrin. Aluminum porphyrin exhibits excellent stability in Lewis acid catalysis systems, and the central aluminum ion possesses additional coordination potential, facilitating functionalization and catalytic site regulation. Furthermore, aluminum porphyrin demonstrates good thermal stability and high structural rigidity, resisting degradation under high-temperature reactions and heterogeneous catalytic conditions, exhibiting excellent catalytic durability and structural support. Compared to other heavy metal porphyrins, aluminum has low toxicity, which is beneficial for large-scale catalyst preparation and environmentally sustainable applications.

[0015] The quaternary phosphine salt is one or a mixture of two or more of the following: methyltriphenylphosphine salt, bis(triphenylphosphine)ammonium chloride, ethyltriphenylphosphine iodide, triphenylbenzylphosphine bromide, and tetraphenylphosphine bromide.

[0016] Preferably, the quaternary phosphine salt is methyltriphenylphosphine salt. The methyl substituent in methyltriphenylphosphine salt is small in size, has low steric hindrance, and is structurally stable, making it less prone to decomposition under strong Lewis acids or heating conditions. Compared to phosphine salts with benzyl or larger substituents, it is more resistant to the reaction environment. Furthermore, it exhibits better solubility in common solvents such as 1,2-dichloroethane, which facilitates uniform dispersion of the reactants and improves crosslinking efficiency.

[0017] The crosslinking agent is one of dimethoxymethane, dichloromethane, p-dichlorobenzene, and dibromo-p-xylene.

[0018] Preferably, the crosslinking agent is dimethoxymethane. Dimethoxymethane exhibits high activity under Friedel-Crafts catalysis, effectively providing methylene bridges to connect aromatic rings, achieving the formation of a dense crosslinked network. Furthermore, it can stably participate in the reaction during deep crosslinking, avoiding side reactions. It also possesses low toxicity and good operability, making it suitable for laboratory and industrial-scale synthesis.

[0019] The molar ratio of the metalloporphyrin to the quaternary phosphine salt is 8:1 to 1:8, preferably 4:1 to 1:4.

[0020] The molar ratio of the total amount of metalloporphyrin and quaternary phosphine salt to the crosslinking agent is 1:0.5 to 1:12, preferably 1:1 to 1:3.

[0021] The reaction solvent is one of 1,2-dichloroethane, cyclohexane, and nitrobenzene.

[0022] Preferably, the reaction solvent is 1,2-dichloroethane. 1,2-Dichloroethane has high solubility for nonpolar organic compounds (such as styrene derivatives) and low solubility for polar products (such as cross-linked polymers), which can promote product precipitation and drive the reaction equilibrium to the forward direction.

[0023] The ratio of the total amount of the metalloporphyrin and quaternary phosphine salt to the amount of reaction solvent is 1 mmol:10 mL to 1 mmol:20 mL.

[0024] The Lewis acid catalyst is one of anhydrous ferric chloride, aluminum chloride, and titanium chloride.

[0025] Preferably, the Lewis acid catalyst is anhydrous ferric chloride. Anhydrous ferric chloride has strong Lewis acidity, can efficiently activate aromatic rings, causing them to undergo electrophilic substitution reactions to form C–C bonds, thereby accelerating the formation of cross-linked networks, and is inexpensive, environmentally friendly, and readily available.

[0026] The molar ratio of the precursor monomer (based on the total amount of metalloporphyrin and quaternary phosphine salt) to the Lewis acid catalyst is 1:1 to 1:16, preferably 1:3 to 1:9, and more preferably 1:3 to 1:6.

[0027] In step (2), the temperature of the Friedel-Crafts reaction is 20–90 °C, preferably 75–85 °C, and the reaction time is 12–36 h, preferably 20–28 h.

[0028] The Soxhlet extraction time is 12–36 h, preferably 20–30 h.

[0029] The vacuum drying temperature is 50–90 °C, preferably 60–80 °C, and the vacuum drying time is 12–36 h, preferably 20–30 h.

[0030] Another object of the present invention is to provide the application of the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst in the copolymerization reaction of epoxide and carbon dioxide to prepare carbon dioxide-based polyols.

[0031] Another objective of this invention is to provide a method for catalytic synthesis of carbon dioxide-based polyols, comprising: using the aforementioned porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst as a catalyst, under certain carbon dioxide pressure conditions and in the presence of a chain transfer agent, copolymerizing epoxide with carbon dioxide to prepare carbon dioxide-based polyols; after the reaction is completed, cooling and filtering to recover the catalyst.

[0032] The epoxide can be one or a mixture of two or more of propylene oxide, 1,2-epoxybutane and cyclohexene oxide.

[0033] Preferably, the epoxide is propylene oxide. Propylene oxide is abundant and inexpensive, has moderate ring strain and good reactivity, and can be efficiently copolymerized with carbon dioxide under relatively mild conditions. The reaction process is stable and controllable, with few side reactions, which facilitates precise control of the polymer structure.

[0034] The chain transfer agent is a compound having a carboxyl or hydroxyl group; preferably, the chain transfer agent is one of sebacic acid, pyromellitic acid, 1,2,4,5-benzenetetracarboxylic acid, dipentaerythritol, water, or other compounds having a carboxyl or hydroxyl group structure.

[0035] More preferably, the chain transfer agent is sebacic acid. Sebacic acid, as a chain transfer agent, not only possesses excellent end-group regulation capabilities, effectively controlling the growth of polymer molecular chains and achieving controllable adjustment of product molecular weight, but its structure also has minimal impact on the final product performance, contributing to obtaining a narrower molecular weight distribution (dispersion coefficient). 1.05–1.30) and reactive low molecular weight polyol products.

[0036] The molar ratio of the epoxide to the chain transfer agent is 5:1 to 1000:1, preferably 20:1 to 100:1.

[0037] The mass ratio of the epoxide to the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst is 10:1 to 200:1, preferably 35:1 to 45:1.

[0038] The carbon dioxide pressure is 1 MPa to 6 MPa, preferably 2 to 4 MPa.

[0039] The copolymerization reaction is carried out at a temperature of 20–150 °C, preferably 40–120 °C.

[0040] The copolymerization reaction takes 1 to 36 hours, preferably 3 to 20 hours.

[0041] The carbon dioxide-based polyol has a structure in which carbonate segments and ether segments coexist.

[0042] Preferably, the carbonate segment content in the carbon dioxide-based polyol is 25% to 60%, and the number average molecular weight is 1000 to 3500 g / mol.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] (1) In this invention, metal porphyrin and quaternary phosphine salt are synergistically introduced and covalently fixed in a super-crosslinked porous framework to construct a bifunctional synergistic catalytic site of porphyrin metal center / quaternary phosphine cationic group, forming a multi-site microenvironment that is conducive to the controllable copolymerization of carbon dioxide and epoxide; it still has good catalytic stability and proton tolerance under various chain transfer agents, which is conducive to the preparation of carbon dioxide-based polyols with low to medium molecular weight and high carbonate segment content.

[0045] (2) The present invention uses Friedel-Crafts reaction crosslinking to construct a three-dimensional hypercrosslinked network, which is provided by an external crosslinking agent and enables the controllability of crosslinking degree and pore structure. While increasing the density of quaternary phosphine cation active sites, it can still maintain a high specific surface area, good pore structure and skeleton mechanical stability, and alleviate the problem of decreased porosity or skeleton collapse caused by the increase of functionalization degree in traditional functionalized porous materials.

[0046] (3) The catalyst of this invention is a heterogeneous solid porous material. After the reaction, it can be easily separated and recovered by filtration. After multiple cycles, it can still maintain a high epoxide conversion rate and carbon dioxide-based polyol selectivity. It has both catalytic activity and reusability, providing a new catalytic system option for the large-scale production of carbon dioxide-based polyols. It is suitable for the continuous and scale-up preparation of carbon dioxide-based polyols.

[0047] (4) The catalyst of the present invention can achieve high epoxide conversion rate and carbon dioxide-based polyol selectivity under mild reaction conditions. Attached Figure Description

[0048] Figure 1 The infrared spectrum of the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst 1 prepared in Example 1 is shown.

[0049] Figure 2The infrared spectrum of the carbon dioxide-based polyol prepared in Example 2.

[0050] Figure 3 The image shows the 1H NMR spectrum of the carbon dioxide-based polyol prepared in Example 2. Detailed Implementation

[0051] The technical solution of the present invention will be described in detail below with reference to embodiments. These embodiments are merely descriptions of the best implementation of the present invention and do not limit the scope of protection of the present invention in any way.

[0052] Example 1

[0053] Using 5,10,15,20-tetraphenylporphyrin aluminum chloride and methyltriphenylphosphine bromide as precursor monomers and dimethoxymethane as a crosslinking agent, 5,10,15,20-tetraphenylporphyrin aluminum chloride, methyltriphenylphosphine bromide, and dimethoxymethane were weighed according to a molar ratio of 1:2 for 5,10,15,20-tetraphenylporphyrin aluminum chloride and methyltriphenylphosphine bromide, and a molar ratio of 1:2 for the precursor monomers (the sum of the moles of 5,10,15,20-tetraphenylporphyrin aluminum chloride and methyltriphenylphosphine bromide) and dimethoxymethane.

[0054] Under nitrogen protection, 5,10,15,20-tetraphenylporphyrin aluminum chloride, methyltriphenylphosphine bromide, and dimethoxymethane were added to a three-necked flask containing anhydrous 1,2-dichloroethane. The mixture was magnetically stirred at room temperature for 1 h to ensure that the precursor monomer and crosslinking agent were fully dissolved and mixed in 1,2-dichloroethane (the ratio of precursor monomer to 1,2-dichloroethane was 1 mmol:15 mL), resulting in a mixed solution. Subsequently, anhydrous ferric chloride was added to the mixed solution at a molar ratio of 6:1 to the precursor monomer (the sum of the molar amounts of 5,10,15,20-tetraphenylporphyrin aluminum chloride and methyltriphenylphosphine bromide). The mixture was heated to 35 °C and stirred for 3 h, then heated to 80 °C and subjected to Friedel-Crafts crosslinking for 24 h with stirring. The resulting suspension was cooled to room temperature and centrifuged for solid-liquid separation. The resulting solid was washed alternately with methanol and deionized water to remove Lewis acid catalyst residue, unreacted precursors, and solvent impurities until the supernatant of the washing liquid was clear and nearly colorless. Then, Soxhlet extraction was performed in methanol at boiling state for 24 h, and finally dried in a vacuum drying oven at 70 ℃ for 24 h to obtain the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst, denoted as catalyst 1.

[0055] The infrared spectrum of catalyst 1 is shown below. Figure 1 FTIR data: 1205 cm -1 The infrared absorption peak belongs to the C–N stretching vibration peak, and this signal is attributed to the core structure of the porphyrin ring. Meanwhile, at 1085 cm⁻¹...-1 The peak belongs to the P–C bond (νP–C) stretching vibration absorption peak, and this signal originates from the quaternary phosphine salt monomer structure. Furthermore, at 2924 cm⁻¹... -1 The peak corresponds to the alkyl C–H stretching vibration introduced by the methylene bridge, proving that the Friedel-Crafts reaction led to the partial alkylation of the phenyl group, thus successfully constructing the cross-linked backbone structure.

[0056] Example 2

[0057] Performance testing:

[0058] A 50 mL stainless steel high-pressure reactor with a built-in magnetic stirrer was selected. The reactor was thoroughly dried beforehand. Under nitrogen protection, 10 mL of propylene oxide, 0.2 g of catalyst 1 (Example 1), and 0.6 g of sebacic acid (chain transfer agent) were added sequentially to the reactor according to a mass ratio of propylene oxide to catalyst 1 of approximately 42:1 and a molar ratio of propylene oxide to sebacic acid of approximately 48:1. The reactor lid was then assembled and the bolts tightened. The gas inside the reactor was repeatedly purged with carbon dioxide to remove residual nitrogen from the system. Subsequently, the heating device was turned on, and the reaction system was heated to 80 °C. Simultaneously, carbon dioxide was introduced into the reactor until the internal pressure reached 2 MPa and was maintained at this pressure. After the temperature and pressure stabilized, stirring was started. Timing was started 5 minutes after stabilization, and the reaction start time was recorded. The reaction was carried out for 8 hours under the above conditions. After the reaction was completed, heating was stopped, and the reactor was allowed to cool naturally to room temperature. Unreacted carbon dioxide was slowly released, the reactor lid was opened, and the reaction mixture was collected. The reaction mixture was filtered to remove solid catalyst 1, and the filtrate was the crude product of carbon dioxide-based polyol. 1 Quantitative analysis of the crude product was performed using ¹H NMR to calculate the conversion rate of propylene oxide and the selectivity of the carbon dioxide-based polyol. The carbonate segment content was determined based on the integral ratio of the characteristic peaks of the carbonate and ether segments. Subsequently, residual propylene oxide in the crude carbon dioxide-based polyol product was removed using a vacuum drying oven at 25 °C and a vacuum of -0.085 to -0.095 MPa (relative to atmospheric pressure), yielding the carbon dioxide-based polyol product.

[0059] The infrared spectrum of the obtained carbon dioxide-based polyol product is as follows: Figure 2 As shown, FTIR data: 1748 cm -1 and 1253cm -1 The absorption peak corresponds to the C=O and CO stretching vibrations in the carbonate groups of carbon dioxide-based polyols; 2980 cm⁻¹ -1 2941cm -1 2870 cm -1 1458 cm -1 and 1375 cm -1The absorption peak at 1104 cm⁻¹ is attributed to the stretching and bending vibrations of CH₃, CH₂, and CH groups; -1 The absorption peaks in the appendix originate from the vibration of the COC ether bond; 3384–3466 cm⁻¹ -1 The broad peaks indicate the presence of terminal hydroxyl groups (-OH), and the above characteristic peaks together prove that carbon dioxide-based polyols have been generated.

[0060] crude product 1 H NMR such as Figure 3 As shown, the calculated propylene oxide conversion rate was 70.17%, the selectivity of the carbon dioxide-based polyol was 96.27%, and the carbonate segment (CU) content was 50.59%. The number-average molecular weight M of the carbon dioxide-based polyol product was determined by GPC. n It is 2542 g / mol, and the molecular weight distribution coefficient is... It is 1.15.

[0061] Example 3

[0062] Referring to the method of Example 1, catalysts 2-15 were prepared by changing the metal active centers of the precursor metalloporphyrin (5,10,15,20-tetraphenylporphyrin, including 5,10,15,20-tetraphenylporphyrin aluminum chloride, 5,10,15,20-tetraphenylporphyrin cobalt, 5,10,15,20-tetraphenylporphyrin iron, 5,10,15,20-tetraphenylporphyrin magnesium), precursor quaternary phosphine salt, crosslinking agent, and catalyst according to Table 1. The amounts (molar ratio of metalloporphyrin to quaternary phosphine salt is 1:2, the molar ratio of the sum of the amounts of metalloporphyrin and quaternary phosphine salt to the molar ratio of crosslinking agent is 1:2, and the molar ratio of catalyst to the sum of the amounts of metalloporphyrin and quaternary phosphine salt is 6:1) and the preparation method were the same as in Example 1.

[0063] Table 1. Preparation conditions of catalysts 1-15

[0064] Catalyst Metal active center of porphyrin Quaternary phosphonium salt Crosslinker Catalyst Catalyst 1 Al Methyltriphenylphosphonium bromide Dimethoxymethane Anhydrous ferric chloride Catalyst 2 Al Methyltriphenylphosphonium bromide Dibromo-p-xylene Anhydrous ferric chloride Catalyst 3 Al Triphenylbenzylphosphonium bromide p-Dichlorobenzene Anhydrous ferric chloride Catalyst 4 Co Triphenylbenzylphosphonium bromide Dichloromethane Anhydrous ferric chloride Catalyst 5 Co Triphenylbenzylphosphonium bromide Dimethoxymethane Aluminum chloride Catalyst 6 Fe Tetraphenylphosphonium bromide Dibromo-p-xylene Aluminum chloride Catalyst 7 Co Tetraphenylphosphonium bromide Dichloromethane Aluminum chloride Catalyst 8 Co Tetraphenylphosphonium bromide Dimethoxymethane Titanium chloride Catalyst 9 Fe Methyltriphenylphosphonium iodide Dibromo-p-xylene Titanium chloride Catalyst 10 Fe Methyltriphenylphosphonium iodide p-Dichlorobenzene Titanium chloride Catalyst 11 Fe Methyltriphenylphosphonium bromide Dichloromethane Aluminum chloride Catalyst 12 Mn Bis(triphenylphosphonium) ammonium chloride p-Dichlorobenzene Anhydrous ferric chloride Catalyst 13 Mn Bis(triphenylphosphonium) ammonium chloride Dibromo-p-xylene Titanium chloride Catalyst 14 Al Methyltriphenylphosphonium chloride Dichloromethane Anhydrous ferric chloride Catalyst 15 Mn Methyltriphenylphosphonium chloride Dibromo-p-xylene Aluminum chloride

[0065] Example 4

[0066] Catalyst performance testing

[0067] Under nitrogen protection, 10 mL of propylene oxide, 0.2 g of catalyst, and 0.6242 g of sebacic acid were added to a thoroughly dried 50 mL stainless steel high-pressure reactor. The reactor was sealed, and the nitrogen gas inside was replaced with carbon dioxide. Heating was started and the temperature was raised to the reaction temperature (Table 2). Carbon dioxide was introduced to raise the pressure inside the reactor to the reaction pressure and maintained at this pressure (Table 2). After stirring was started and the mixture was stabilized for 5 min, the reaction time was started, as shown in Table 2. After the reaction was completed, the reaction solution was collected, filtered to remove the catalyst, and analyzed using nuclear magnetic resonance (NMR). The conversion rate of propylene oxide and the selectivity of carbon dioxide-based polyols are shown in Table 2.

[0068] Table 2. Performance test conditions and results for catalysts 1-15

[0069] Catalyst Temperature (°C) Pressure (MPa) Time (h) Conversion of propylene oxide (%) Selectivity of carbon dioxide-based polyol (%) CU (%) M n,GPC (g·mol -1 )]]> Molecular weight distribution coefficient Catalyst 1 60 2 8 70.17 96.27 50.95 2542 1.15 Catalyst 2 80 5 8 64.59 95.68 49.24 1712 1.19 Catalyst 3 80 4 8 61.22 93.44 50.76 1759 1.23 Catalyst 4 80 2 8 52.77 92.22 43.49 2097 1.22 Catalyst 5 120 2.5 10 59.58 96.06 47.29 2472 1.17 Catalyst 6 120 2.5 10 83.92 94.33 45.25 2678 1.21 Catalyst 7 120 2.5 12 67.37 85.63 60.26 2354 1.13 Catalyst 8 70 3 12 63.28 93.47 42.95 2103 1.07 Catalyst 9 100 3 4 60.14 90.25 50.76 2403 1.15 Catalyst 10 100 3 4 53.79 97.12 45.11 1162 1.22 Catalyst 11 100 3 4 58.89 96.81 49.37 2103 1.07 Catalyst 12 50 2 20 58.62 93.85 54.57 1243 1.19 Catalyst 13 60 2 6 69.70 95.95 49.58 2272 1.20 Catalyst 14 60 1 6 54.35 96.26 58.57 1064 1.19 Catalyst 15 40 6 6 60.03 96.33 49.18 2738 1.09 Catalyst 15 60 2 8 72.39 97.38 50.19 2398 1.04 Catalyst 15 120 1 3 68.24 96.74 48.27 2485 1.07 Catalyst 15 80 3 6 70.94 97.32 42.75 2345 1.12 Catalyst 15 40 5 12 63.25 96.79 49.37 2517 1.12

[0070] Note: CU represents the carbonate content in carbon dioxide-based polyols; M n,GPC The number-average molecular weight of carbon dioxide-based polyols was determined by gel permeation chromatography.

[0071] Example 5

[0072] Catalyst 16 was prepared according to the method of Example 1. In the preparation process, only the molar ratio of 5,10,15,20-tetraphenylporphyrin aluminum chloride to methyltriphenylphosphine bromide in Example 1 was replaced with 1:1, while other conditions remained unchanged.

[0073] Catalyst 17 was prepared according to the method of Example 1. In the preparation process, only the molar ratio of 5,10,15,20-tetraphenylporphyrin aluminum chloride to methyltriphenylphosphine bromide in Example 1 was replaced with 2:1, while other conditions remained unchanged.

[0074] Catalyst 18 was prepared according to the method of Example 1. During the preparation process, only the molar ratio of 5,10,15,20-tetraphenylporphyrin aluminum chloride to methyltriphenylphosphine bromide in Example 1 was replaced with 4:1, while other conditions remained unchanged.

[0075] Catalyst 19 was prepared according to the method of Example 1. In the preparation process, only the molar ratio of 5,10,15,20-tetraphenylporphyrin aluminum chloride to methyltriphenylphosphine bromide in Example 1 was replaced with 1:4, while other conditions remained unchanged.

[0076] Catalyst 20 was prepared according to the method of Example 1. During the preparation process, only the molar ratio of the crosslinking agent to the precursor monomer in Example 1 was replaced with 3:1, while other conditions remained unchanged.

[0077] Catalyst 21 was prepared according to the method of Example 1. During the preparation process, only the molar ratio of the crosslinking agent to the precursor monomer in Example 1 was replaced with 1:1, while other conditions remained unchanged.

[0078] Table 3. Preparation conditions of catalysts 16-21

[0079] Catalyst Molar ratio of porphyrin to quaternary phosphonium salt Molar ratio of crosslinker to precursor monomer Catalyst 1 1:2 2:1 Catalyst 16 1:1 2:1 Catalyst 17 2:1 2:1 Catalyst 18 4:1 2:1 Catalyst 19 1:4 2:1 Catalyst 20 1:2 3:1 Catalyst 21 1:2 1:1

[0080] The performance of catalysts 16-21 was tested according to the performance test conditions of Example 2, and the analysis results are shown in Table 4.

[0081] Table 4. Performance test results of catalysts 16-21

[0082] Catalyst Conversion of propylene oxide (%) Selectivity of carbon dioxide-based polyol (%) CU (%) M n,GPC (g·mol -1 )]]> Molecular weight distribution coefficient Catalyst 1 70.17 96.27 50.95 2542 1.15 Catalyst 16 49.89 91.11 44.55 1876 1.22 Catalyst 17 62.78 86.66 45.98 2304 1.19 Catalyst 18 67.51 95.41 43.31 1450 1.25 Catalyst 19 58.64 93.50 41.75 1628 1.23 Catalyst 20 61.06 95.95 39.54 1763 1.17 Catalyst 21 54.35 97.26 43.57 2410 1.11

[0083] Example 6

[0084] Following the preparation method of Example 1, only the pre-crosslinking reaction temperature and time, and the Friedel-Crafts reaction temperature and time were changed to prepare catalysts 22 and 25.

[0085] Table 5. Preparation conditions of catalysts 22-25

[0086] Catalyst Pre-crosslinking reaction temperature Pre-crosslinking reaction time Friedel-Crafts reaction temperature Friedel-Crafts reaction time Catalyst 1 35 3 80 24 Catalyst 22 25 6 75 28 Catalyst 23 30 5 78 25 Catalyst 24 45 2 85 20 Catalyst 25 40 4 80 22

[0087] The performance of catalysts 22-25 was tested according to the performance test conditions of Example 2, and the analysis results are shown in Table 6.

[0088] Table 6. Performance test results of catalysts 22-25

[0089] Catalyst Conversion of propylene oxide (%) Selectivity of carbon dioxide-based polyol (%) CU (%) M n,GPC (g·mol -1 )]]> Molecular weight distribution coefficient Catalyst 1 70.17 96.27 50.95 2542 1.15 Catalyst 22 68.34 95.42 49.24 2419 1.13 Catalyst 23 64.79 95.97 48.92 2564 1.19 Catalyst 24 65.81 96.19 50.23 2592 1.09 Catalyst 25 64.73 94.92 48.93 2623 1.18

[0090] Example 7

[0091] Carbon dioxide-based polyol product 26 was prepared according to the method of Example 2. In the preparation process, only the propylene oxide in Example 2 was replaced with an equal mass of 1,2-epoxybutane, while other conditions remained unchanged.

[0092] Carbon dioxide-based polyol product 27 was prepared according to the method of Example 2. In the preparation process, only the propylene oxide in Example 2 was replaced with an equal mass of cyclohexene oxide, while other conditions remained unchanged.

[0093] Carbon dioxide-based polyol product 28 was prepared according to the method of Example 2. During the preparation process, only the chain transfer agent sebacic acid in Example 2 was replaced with an equal mass of trimesic acid; all other conditions remained unchanged.

[0094] Carbon dioxide-based polyol product 29 was prepared according to the method of Example 2. During the preparation process, only the chain transfer agent sebacic acid in Example 2 was replaced with an equal mass of 1,2,4,5-benzenetetracarboxylic acid, while other conditions remained unchanged.

[0095] Carbon dioxide-based polyol product 30 was prepared according to the method of Example 2. During the preparation process, only the chain transfer agent sebacic acid in Example 2 was replaced with an equal mass of dipentaerythritol, while all other conditions remained unchanged.

[0096] Carbon dioxide-based polyol product 31 was prepared according to the method of Example 2. During the preparation process, only the chain transfer agent sebacic acid in Example 2 was replaced with an equal mass of water, while other conditions remained unchanged.

[0097] Carbon dioxide-based polyol product 32 was prepared according to the method of Example 2. During the preparation process, only the chain transfer agent sebacic acid in Example 2 was replaced with an equal mass of polyethylene glycol (Mn≈300 g / mol), while other conditions remained unchanged. The performance of products 26-32 was evaluated according to the performance testing conditions of Example 2, and the analysis results are shown in Table 7.

[0098] Table 7. Preparation conditions and performance evaluation results of products 26-32

[0099] Product Epoxide Chain transfer agent Conversion of propylene oxide (%) Selectivity of carbon dioxide-based polyol (%) CU (%) M n,GPC (g·mol -1 )]]> Molecular weight distribution coefficient Product 1 Propylene oxide Sebacic acid 70.17 96.27 50.95 2542 1.15 Product 26 1,2-Epoxybutane Sebacic acid 50.66 97.16 50.59 2678 1.13 Product 27 Cyclohexene oxide Sebacic acid 58.47 93.88 39.12 2187 1.19 Product 28 Propylene oxide Trimesic acid 42.31 92.76 40.35 1825 1.23 Product 29 Propylene oxide 1,2,4,5-Benzenetetracarboxylic acid 71.92 96.12 43.45 1482 1.12 Product 30 Propylene oxide Dipentaerythritol 68.64 95.45 44.78 1376 1.17 Product 31 Propylene oxide Water 61.25 94.73 43.12 1659 1.20 Product 32 Propylene oxide Polyethylene glycol 56.92 90.21 41.22 1128 1.28

[0100] Example 8

[0101] Carbon dioxide-based polyol product 33 was prepared according to the method of Example 2, except that the molar ratio of propylene oxide to sebacic acid was adjusted to 20:1 and the mass ratio of propylene oxide to catalyst 1 was adjusted to 38:1, while other conditions remained unchanged.

[0102] Carbon dioxide-based polyol product 34 was prepared according to the method of Example 2, except that the molar ratio of propylene oxide to sebacic acid in Example 2 was adjusted to 65:1 and the mass ratio of propylene oxide to catalyst 1 was adjusted to 40:1, while other conditions remained unchanged.

[0103] Carbon dioxide-based polyol product 35 was prepared according to the method of Example 2, except that the molar ratio of propylene oxide to sebacic acid in Example 2 was adjusted to 86:1 and the mass ratio of propylene oxide to catalyst 1 was adjusted to 45:1, while other conditions remained unchanged.

[0104] Carbon dioxide-based polyol product 36 was prepared according to the method of Example 2, except that the molar ratio of propylene oxide to sebacic acid in Example 2 was adjusted to 100:1, and the mass ratio of propylene oxide to catalyst 1 was adjusted to 35:1, while other conditions remained unchanged.

[0105] The performance of products 33-36 was evaluated according to the performance test conditions of Example 2, and the analysis results are shown in Table 8.

[0106] Table 8. Preparation conditions and performance evaluation results of products 33-36

[0107] Product Molar ratio of epoxide to chain transfer agent Mass ratio of epoxide to catalyst Conversion of propylene oxide (%) Selectivity of carbon dioxide-based polyol (%) CU (%) M n,GPC (g·mol -1 )]]> Molecular weight distribution coefficient Product 1 48:1 42:1 70.17 96.27 50.95 2542 1.15 Product 33 20:1 38:1 68.74 95.31 49.21 1974 1.14 Product 34 65:1 40:1 67.68 93.47 43.28 2619 1.08 Product 35 86:1 45:1 68.83 95.31 46.26 2677 1.19 Product 36 100:1 35:1 66.54 93.64 46.78 2796 1.18

[0108] Example 9

[0109] Repeatability test

[0110] A carbon dioxide-based polyol was prepared by copolymerizing porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst 1 under the copolymerization conditions of Example 2. After the reaction, the solid catalyst was recovered by centrifugation, washed with ethyl acetate and dichloromethane, and dried under vacuum at 60 °C for 12 h. The recovered catalyst was used in the next round of reaction under the same conditions, and was continuously recycled 6 times.

[0111] The cyclic performance of catalyst 1 is shown in Table 9. As can be seen from Table 9, with the increase of the number of cycles, the conversion rate of propylene oxide (Conv. of PO) decreased successively from 70.17% in the first reaction to 67.63% in the second, 63.13% in the third, 57.21% in the fourth, and 54.83% in the fifth, but remained at 52.28% in the sixth cycle, indicating that the catalyst still has high catalytic activity after multiple reuses. The selectivity of carbon dioxide-based polyols remained above 95% throughout the entire cycle, demonstrating high product selectivity.

[0112] Table 9. Cyclic stability results of catalyst 1

[0113] Number of times used propylene oxide conversion rate (%) Carbon dioxide-based polyol selectivity (%) CU(%) M n,GPC (g·mol -1 )]]> Molecular weight distribution coefficient 1 70.17 96.27 50.95 2542 1.15 2 67.63 97.40 55.40 2729 1.17 3 63.13 92.81 45.42 2221 1.16 4 57.21 95.67 41.76 2198 1.21 5 54.83 96.32 49.25 2153 1.20 6 52.28 95.64 42.90 1916 1.19

[0114] Comparative Example 1

[0115] Dimethoxymethane, 5,10,15,20-tetraphenylporphyrin aluminum chloride, and anhydrous ferric chloride were weighed according to a molar ratio of 2:1 for dimethoxymethane and 1:1 for anhydrous ferric chloride.

[0116] Under nitrogen protection, 5,10,15,20-tetraphenylporphyrin aluminum chloride and dimethoxymethane were added to a three-necked flask containing anhydrous 1,2-dichloroethane. The mixture was magnetically stirred at room temperature for 1 h, and then anhydrous ferric chloride was rapidly added. Subsequently, the mixture was stirred at 35 °C for 3 h, and then heated to 80 °C and stirred for 24 h. The resulting suspension was cooled to room temperature and centrifuged for solid-liquid separation. The obtained solid was washed repeatedly with methanol and deionized water until the supernatant of the washings was clear and nearly colorless. Then, Soxhlet extraction was performed at boiling point using methanol as a solvent for 24 h. Finally, the solid was dried in a vacuum drying oven at 70 °C for 24 h to obtain comparative catalyst 1.

[0117] Under nitrogen protection, 10 mL of propylene oxide, 0.2 g of comparative catalyst 1, and 0.6 g of sebacic acid were added to a thoroughly dried 50 mL stainless steel high-pressure reactor. The reactor was sealed, and the nitrogen gas inside was replaced with carbon dioxide. Heating was started and the temperature was raised to the reaction temperature of 80 °C. Carbon dioxide was introduced to raise the pressure inside the reactor to the reaction pressure of 2 MPa and maintained at this reaction pressure of 2 MPa. After stirring was started and the mixture stabilized for 5 min, the reaction time was started and the reaction was carried out for 8 h. After the polymerization reaction was completed, the mixture was cooled to room temperature, and the remaining CO2 was slowly released. The reaction solution was collected, filtered to remove the catalyst from the reaction solution, and carbon dioxide polyol product was obtained. Nuclear magnetic resonance analysis showed that the conversion rate of propylene oxide was 20.37%, the selectivity of carbon dioxide-based polyol was 85.12%, the carbonate content in the carbon dioxide-based polyol was 30.37%, and the number average molecular weight M was [missing value]. n The molecular weight distribution coefficient was 2684 g / mol, and the molecular weight distribution coefficient was 1.21. Using catalyst 1, under the same conditions, the propylene oxide conversion rate was 70.17%, the selectivity for carbon dioxide-based polyols was 96.27%, the carbonate segment content was 50.59%, and the number-average molecular weight M... n It has a concentration of 2542 g / mol and a molecular weight distribution coefficient of 1.15.

[0118] Compared to catalyst 1, which lacks a quaternary phosphine salt functional unit as a precursor and thus lacks ionic sites that synergize with the porphyrin metal center, catalyst 1 exhibits insufficient CO2 enrichment and insertion capabilities. Furthermore, its inhibition of side reactions such as propylene oxide self-polymerization is weakened, leading to a decrease in the CO2 insertion ratio, as well as reduced conversion and product selectivity. This indicates that the bifunctional synergy between the quaternary phosphine salt and the porphyrin metal center is crucial for achieving high activity and high carbonate content.

[0119] Comparative Example 2

[0120] Benzene, methyltriphenylphosphine bromide, dimethoxymethane, and anhydrous ferric chloride are weighed according to the following molar ratios: benzene to methyltriphenylphosphine bromide is 1:2, dimethoxymethane to precursor monomer (the sum of benzene and methyltriphenylphosphine bromide) is 2:1, and anhydrous ferric chloride to dimethoxymethane is 1:1.

[0121] Under nitrogen protection, benzene, methyltriphenylphosphine bromide, and dimethoxymethane were added to a three-necked flask containing anhydrous 1,2-dichloroethane. After magnetic stirring at room temperature for 1 h, anhydrous ferric chloride catalyst was rapidly added. Subsequently, the mixture was stirred at 35 °C for 3 h, then heated to 80 °C and stirred for 24 h. The resulting suspension was cooled to room temperature and centrifuged for solid-liquid separation. The obtained solid was washed repeatedly with methanol and deionized water until the supernatant was clear and nearly colorless. Then, Soxhlet extraction was performed at boiling point using methanol as solvent for 24 h. Finally, the solid was dried in a vacuum drying oven at 70 °C for 24 h to obtain control catalyst 2.

[0122] Under nitrogen protection, 10 mL of propylene oxide, 0.2 g of comparative catalyst 2, and 0.6 g of sebacic acid were added to a thoroughly dried 50 mL stainless steel high-pressure reactor. The reactor was sealed, and the nitrogen gas inside was replaced with carbon dioxide. Heating was started and the temperature was raised to the reaction temperature of 80 °C. Carbon dioxide was introduced to raise the pressure inside the reactor to the reaction pressure of 2 MPa and maintained at this reaction pressure of 2 MPa. After stirring was started and the mixture stabilized for 5 min, the reaction time was started and the reaction was carried out for 8 h. After the polymerization reaction was completed, the mixture was cooled to room temperature, and the remaining CO2 was slowly released. The reaction solution was collected, filtered to remove the catalyst from the reaction solution, and carbon dioxide polyol product was obtained. Nuclear magnetic resonance analysis showed that the conversion rate of propylene oxide was 19.79%, the selectivity of carbon dioxide-based polyol was 72.58%, the carbonate content in the carbon dioxide-based polyol was 24.04%, and the number average molecular weight M was [missing value]. n It has a concentration of 2284 g / mol and a molecular weight distribution coefficient of 1.18.

[0123] Compared with catalyst 2, which uses benzene as a precursor, catalyst 2 lacks the key active site of porphyrin metal center, and cannot effectively coordinate and activate propylene oxide and promote CO2 insertion. At the same time, benzene only provides a crosslinkable aromatic ring skeleton, making it difficult to form a bifunctional catalytic system of "metal site-ion site" in synergy with quaternary phosphine salt. As a result, the reaction mainly follows competitive pathways such as propylene oxide self-polymerization, and therefore the conversion, selectivity and CU are all lower than those of the catalyst system containing metal porphyrin.

Claims

1. A porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst, characterized in that: It is a three-dimensional hypercrosslinked polymer framework constructed by Friedel-Crafts reaction under Lewis acid catalysis, using metal porphyrin and quaternary phosphine salt as precursor monomers and crosslinking agent as crosslinking unit. The metal center of metal porphyrin and the cationic functional groups of quaternary phosphine salt are distributed in the three-dimensional hypercrosslinked polymer framework.

2. A method for preparing the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst according to claim 1, characterized in that: Includes the following steps: Step (1): Using metal porphyrin and quaternary phosphine salt as precursor monomers, under a nitrogen or inert gas atmosphere, metal porphyrin, quaternary phosphine salt, Lewis acid catalyst and crosslinking agent are dissolved in an organic solvent to carry out a pre-crosslinking reaction to obtain a preliminary crosslinking intermediate. Step (2): Based on the preliminary crosslinking intermediate obtained in step (1), the reaction temperature is increased to allow the system to undergo a Friedel-Crafts type crosslinking reaction. After the reaction is completed, the product is washed with methanol and deionized water, extracted with methanol using Soxhlet extraction, and dried under vacuum to obtain the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst.

3. The preparation method of the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst according to claim 2, characterized in that: In step (1), the temperature of the pre-crosslinking reaction is 15-65 ℃, preferably 25-45 ℃, and the time of the pre-crosslinking reaction is 1-10 h, preferably 2-6 h; in step (2), the temperature of the Friedel-Crafts reaction is 20-90 ℃, preferably 75-85 ℃, and the time of the Friedel-Crafts reaction is 12-36 h, preferably 20-28 h; the Soxhlet extraction time is 12-36 h, preferably 20-30 h.

4. The method for preparing the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst according to claim 2, characterized in that: In step (1), the metalloporphyrin is one of aluminum porphyrin, cobalt porphyrin, iron porphyrin, and magnesium porphyrin, preferably aluminum porphyrin; the quaternary phosphine salt is one or a mixture of two or more of methyltriphenylphosphine salt, bis(triphenylphosphine)ammonium chloride, ethyltriphenylphosphine iodide, triphenylbenzylphosphine bromide, and tetraphenylphosphine bromide, preferably methyltriphenylphosphine salt; the crosslinking agent is one of dimethoxymethane, dichloromethane, p-dichlorobenzene, and dibromo-p-xylene, preferably dimethoxymethane.

5. The method for preparing the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst according to claim 2 or 4, characterized in that: In step (1), the molar ratio of the metalloporphyrin to the quaternary phosphine salt is 8:1 to 1:8, preferably 4:1 to 1:4; the molar ratio of the total amount of the metalloporphyrin and the quaternary phosphine salt to the crosslinking agent is 1:0.5 to 1:12, preferably 1:1 to 1:

3.

6. The method for preparing the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst according to claim 2, characterized in that: In step (1), the reaction solvent is one of 1,2-dichloroethane, cyclohexane, and nitrobenzene, preferably 1,2-dichloroethane; the ratio of the total amount of metalloporphyrin and quaternary phosphine salt to the amount of reaction solvent is 1 mmol:10 mL to 1 mmol:20 mL; the Lewis acid catalyst is one of anhydrous ferric chloride, aluminum chloride, and titanium chloride, preferably anhydrous ferric chloride; the molar ratio of the precursor monomer to the Lewis acid catalyst is 1:1 to 1:16, preferably 1:3 to 1:

9.

7. A method for catalytic synthesis of carbon dioxide-based polyols, characterized in that: include: Using the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst of claim 1 as the catalyst, under certain carbon dioxide pressure conditions and in the presence of a chain transfer agent, epoxide and carbon dioxide undergo a copolymerization reaction to prepare carbon dioxide-based polyols; after the reaction is completed, the temperature is lowered and the catalyst is recovered by filtration.

8. The method for catalytic synthesis of carbon dioxide-based polyols according to claim 7, characterized in that: The epoxide is one or a mixture of two or more of propylene oxide, 1,2-epoxybutane, and cyclohexene oxide, preferably propylene oxide; the chain transfer agent is a compound having a carboxyl or hydroxyl group, preferably one of sebacic acid, trimesic acid, 1,2,4,5-benzenetetracarboxylic acid, dipentaerythritol, water, or other compounds having a carboxyl or hydroxyl group structure, more preferably sebacic acid.

9. The method for catalytic synthesis of carbon dioxide-based polyols according to claim 7, characterized in that: The molar ratio of the epoxide to the chain transfer agent is 5:1 to 1000:1, preferably 20:1 to 100:1; the mass ratio of the epoxide to the porphyrin-quaternary phosphine salt bifunctional synergistic hypercrosslinked polymer catalyst is 10:1 to 200:1, preferably 35:1 to 45:

1.

10. The method for catalytic synthesis of carbon dioxide-based polyols according to claim 7, characterized in that: The carbon dioxide pressure is 1–6 MPa, preferably 2–4 MPa; the copolymerization temperature is 20–150 °C, preferably 40–120 °C; and the copolymerization time is 1–36 h, preferably 3–20 h.

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