A low molecular weight high activity polyisobutylene and a method for its preparation

Abstract

The application relates to a low-molecular-weight high-activity polyisobutylene and a preparation method thereof, and belongs to the field of high-molecular-weight compound preparation. The preparation method utilizes a simple initiator, a co-initiator and a third component system to catalytically prepare a low-molecular-weight high-activity polyisobutylene. Specifically, a simple and easily-obtained initiator and a Lewis acid with relatively weak corrosion to equipment are used as the co-initiator, a relatively high temperature (-30 DEG C to 0 DEG C) is used, a three-component catalytic system is regulated, and a process flow is optimized, so that the low-molecular-weight high-activity polyisobutylene with an external olefin proportion of 90% is obtained.

Description

Technical Field

[0001] This invention belongs to the field of polymer compound preparation, specifically relating to a low molecular weight, highly active polyisobutylene and its preparation method. Background Technology

[0002] Polyisobutylene (PIB) is a linear saturated polyolefin polymer synthesized from isobutylene monomers through cationic polymerization. It possesses unique chemical structure and performance characteristics, and has wide applications in industry, medicine, and energy. Based on molecular weight, PIB is classified into low molecular weight PIB, medium molecular weight PIB, and high molecular weight PIB. Generally, low molecular weight PIB is defined as having a molecular weight (Mn) between 500-5000 g / mol. Highly reactive polyisobutylene (HR PIB) is a linear polyolefin polymer with a high content of terminal double bonds, reaching over 60%, and can chemically react with monomers of various functional groups. Like ordinary PIB products, HR PIB exhibits excellent chemical corrosion resistance and aging resistance, as well as outstanding low-temperature fluidity and thermal stability. It also shows good compatibility with organic solvents and oils at room temperature. It is mainly used in ashless dispersants, emulsifiers for emulsion explosives, surfactants, detergents, and rust inhibitors, and is particularly irreplaceable in the field of ashless dispersants. In recent years, with the increase in the use of lubricating oil additives, the use of highly active polyisobutylene has shown a year-on-year increasing trend.

[0003] In the polymerization of highly reactive polyisobutylene (HRPIB), BF3, TiCl4, and AlCl3 are commonly used as co-initiators. However, the reaction system suffers from severe isomerization, making it difficult to further increase the content of foreign olefins. Existing commercially available HRPIBs utilize BASF technology, employing a BF3 complex catalyst in patents such as CN00130281.7. This reaction prepares highly reactive HRPIBs at relatively high temperatures. However, this type of polymerization method requires multiple polymerization stages, is complex, demands strict purity of raw materials, and is subject to the highly toxic and corrosive nature of boron trifluoride, making post-processing difficult. Polymer products containing fluorine impurities, when used in the synthesis of fuel additives or lubricating oil additives and further applied to engines, release HF, leading to equipment corrosion and damage.

[0004] In recent years, environmental protection standards in the field of lubricating oils and fuel additives have been continuously improved, and new synthesis processes for highly reactive polyisobutylene (HRPIB) have also been continuously developed. Currently, the mainstream preparation routes are mainly divided into two categories: one is based on living cationic polymerization, using quenching of the polymerization end groups to prepare HRPIB. Common quenching reagents include allyltrimethylsilane (ATMS), sterically hindered bases, and sulfide and ether compounds; the other uses a conventional cationic polymerization system, with complexes formed by metal halides and ethers as co-initiators for isobutylene polymerization. This system initially used AlCl3 / R2O as a catalytic combination, and subsequently, FeCl3 / R2O and TiCl4 catalytic systems were developed for HRPIB synthesis. To improve the solubility of AlCl3 catalysts in non-polar solvents, researchers further developed the RAlCl2 / R2O catalytic system, which can be used to synthesize highly reactive polyisobutylene.

[0005] Patent CN101955558A uses a FeCl3 / oxygen- or sulfur-containing organic compound co-initiating system to prepare highly active polyisobutylene. By introducing oxygen- or sulfur-containing organic compound complexing agents into the polymerization system, the β-H removal reaction of the active center carbocation is promoted, and the formation of tertiary chlorine end groups is reduced, thereby directly preparing highly active polyisobutylene with a high content of terminal α-double bonds. However, the yield of highly active polyisobutylene prepared by this method is low in some examples, and the molecular weight distribution is wide.

[0006] Patent CN103965381A uses a TiCl4 / organic compound additive co-initiation system to prepare highly active polyisobutylene. By introducing organic compound additives, composed of components A (thiols, thioethers, etc.) and components B (phenols, alcohols, etc.), into the polymerization system, the acidity of the counterion is reduced and its nucleophilicity and steric hindrance are increased. This allows for the efficient and selective removal of β-H from the adjacent -CH3 group of the active chain-terminal carbocation, resulting in an α-double bond structure at the end of the polyisobutylene chain, thus directly preparing highly active polyisobutylene. However, the yield of highly active polyisobutylene prepared by this method fluctuates greatly, and the cost of some additives is relatively high.

[0007] Patent CN101613423A mainly uses AlR (3-n) Cl nThe / R2O co-initiation system is used to prepare highly reactive polyisobutylene. By introducing organic compound additives into the polymerization system, the β-H on the adjacent -CH3 group of the active chain terminal carbocation is efficiently and selectively removed, resulting in an α-double bond structure at the polyisobutylene chain terminal, thus directly preparing highly reactive polyisobutylene. Although the highly reactive polyisobutylene prepared by this method has an α-double bond ratio as high as 96%, it suffers from the problem of "high olefin content accompanied by low yield" (for example, the isobutylene conversion rate in Example 2 was only 26%), and the molecular weight distribution is relatively wide. A wide molecular weight distribution will significantly reduce its reactivity and modification efficiency, product performance uniformity, and increase processing and purification costs, which is one of the core technical bottlenecks for high-end applications (such as lubricating oil dispersants and fuel detergents).

[0008] In summary, existing technologies suffer from several problems, including the strong corrosiveness of Lewis acids to equipment, difficulty in controlling the selectivity of highly active end-group double bonds, and low yields associated with high content of foreign olefins. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in current technologies by providing a low molecular weight, highly active polyisobutylene and its preparation method. Unlike previous two-component systems, this invention employs a three-component catalytic system consisting of an initiator, a co-initiator (aluminum-based Lewis acid), and a third component. This system provides a "dual control switch" for the polymerization reaction: the initiator initiates polymerization and controls the chain growth start point, while the third component specifically regulates the active centers of the aluminum-based acid. This provides more precise control than a two-component catalytic system, allowing for more targeted suppression of internal olefin formation and retention of more external olefins. By using a readily available initiation system and a Lewis acid with an ether (electron donor) that is relatively less corrosive to equipment as the co-initiation system, the system reduces the Lewis acid strength by complexing the co-initiator centers with the ether. This system can suppress proton transfer, isomerization, and the formation of internal olefins, making the polymer chains more inclined to form terminal vinylides. Simultaneously, this system has fewer and more uniform active centers, resulting in a significantly narrower molecular weight distribution. Furthermore, it exhibits higher and more stable catalytic activity and better reproducibility. Moreover, this system does not require deep cryogenic temperatures; high-activity polymerization can be achieved at temperatures ranging from -30°C to 0°C. Finally, by adjusting the three-component catalytic system and optimizing the process flow at a relatively high temperature, low molecular weight, highly active polyisobutylene with a number average molecular weight (Mn) of 460-5300 g / mol can be obtained.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] The low molecular weight, high activity polyisobutylene of the present invention uses an initiator, a co-initiator and a third component as a catalytic system, and uses isobutylene as a monomer to polymerize low molecular weight, high activity polyisobutylene.

[0012] The initiator for the highly reactive polyisobutylene is selected from one or more of the following: methyl benzoate, 2-phenylisopropanol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol, methylbenzyl alcohol, 1-(2-methylphenyl)ethanol, 1-(4-methylphenyl)ethanol, 1-phenyl-1-propanol, diphenylethanol, 2-hydroxybenzyl alcohol, 4-methoxybenzyl alcohol, 1-(4-methoxyphenyl)ethanol, 2,6-dimethylbenzyl alcohol, 4-tert-butylbenzyl alcohol, 2-phenyl-2-propanol, 2-(p-tolyl)prop-2-ol, 2-(4-methoxyphenyl)prop-2-ol, and 2-(4-chlorophenyl)prop-2-ol. Preferably, it is selected from one or more of the following: 2-phenylisopropanol, 1-phenyl-1-propanol, 4-methylbenzyl alcohol, 1-phenylethanol, 1-(2-methylphenyl)ethanol, and 1-(4-methylphenyl)ethanol.

[0013] The co-initiator for the highly active polyisobutylene is selected from one or more of the following: trimethylaluminum, triethylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, dichloroethylaluminum, and dichloroisobutylaluminum. Preferably, one or more of dichloroethylaluminum and monochlorodiethylaluminum are selected.

[0014] The third component of the highly reactive polyisobutylene is selected from one or more of the following: benzyl methyl ether, benzyl ethyl ether, benzyl phenyl ether, phenyl ethyl ether, dibenzyl ether, dichloroethyl ether, dibromoethyl ether, m-bromoanisole, p-bromoanisole, 4-iodophenylanisole, dioxane, and N,N-dimethylaniline. Preferably, it is selected from one or more of dichloroethyl ether, dibromoethyl ether, m-bromoanisole, and p-bromoanisole.

[0015] Preferably, when the initiator is selected from one or more of 2-phenylisopropanol, 1-phenyl-1-propanol, 4-methylbenzyl alcohol, 1-phenylethanol, 1-(2-methylphenyl)ethanol, and 1-(4-methylphenyl)ethanol, the co-initiator is selected from one or more of dichloroethylaluminum and monochlorodiethylaluminum, and the third component is selected from one or more of dichloroethyl ether, dibromoethyl ether, m-bromoanisole, and p-bromoanisole, the resulting low molecular weight, highly active polyisobutylene has a conversion rate of over 71%, an external olefin content of over 90%, and a molecular weight distribution of less than 1.52.

[0016] The method for preparing low molecular weight, highly active polyisobutylene of the present invention more specifically includes the following steps:

[0017] S1: Material preparation:

[0018] The polymerization reaction system is an anhydrous and oxygen-free inert gas environment. The dehydrated and deoxygenated organic solvent, dehydrated and deoxygenated isobutylene monomer, initiator, co-initiator, and third component are all stored in an inert environment.

[0019] S2: Aggregation:

[0020] Choose one of the following two polymerization methods:

[0021] The first method involves adding an initiator to a low-temperature isothermal reactor to replace it with an anhydrous and oxygen-free inert gas environment, adding a third component, an organic solvent, and isobutylene monomer, stirring until homogeneous, and obtaining a polymerization system. A co-initiator is then added to initiate the polymerization reaction. After polymerization, a terminator is added to terminate the reaction and obtain the polymerization product.

[0022] The second method: First, replace the low-temperature constant temperature reactor with an anhydrous and oxygen-free inert gas environment, react the co-initiator and the third component to form a complex, then add the initiator, stir evenly, and after stabilization, take out the catalytic system and add it to a solution containing isobutylene monomer to form a polymerization system for catalytic polymerization. After the polymerization is completed, add a terminator to terminate the polymerization and obtain the polymerization product.

[0023] S3: Post-processing:

[0024] The polymerization product was washed with deionized water to remove unreacted isobutylene monomers and organic solvents, and then dried to obtain low molecular weight, highly reactive polyisobutylene.

[0025] In S1, the organic solvent is selected from one or more of the following: n-hexane, tetrahydrofuran, chloromethane, dichloromethane, toluene, chloroethane, vinyl chloride, and propane.

[0026] In S1, the inert gas is preferably nitrogen or argon.

[0027] In S2, the inert gas is either nitrogen or argon.

[0028] In the polymerization system, the mass concentration of isobutylene (IB) monomer is 5~50 wt%.

[0029] The molar ratio of initiator to co-initiator is (0.01~1):1.

[0030] The molar ratio of the third component to the co-initiator is (1.5~5):1.

[0031] The co-initiator accounts for 0.02~10 wt% of the monomer.

[0032] The equilibrium temperature of the low-temperature isothermal reactor is -30~0℃.

[0033] The polymerization time is 5~60 min.

[0034] The co-initiator is added as follows: when there is only one co-initiator, it is added slowly dropwise at a rate of 0.5 to 2 mL / min; when there are two or more co-initiators, the two co-initiators are added slowly dropwise sequentially at intervals of 0 to 45 min at a rate of 0.5 to 2 mL / min.

[0035] The terminator is selected from water, anhydrous methanol, anhydrous ethanol, or an ethanol / water mixed solution containing 1 wt% NaOH; the ethanol:water ratio in the ethanol / water mixed solution is 1:1 (volume ratio); the amount of terminator is 1~5% of the volume percentage of the polymerization system.

[0036] In step S3, the method for removing unreacted isobutylene monomer and organic solvent is vacuum evaporation.

[0037] In S3, the drying process parameters are: pressure -0.1MPa, drying at 40~80℃ to constant weight.

[0038] The present invention discloses a low molecular weight, highly active polyisobutylene, which is prepared by the above-mentioned method with a yield of 62-99%. When the prepared low molecular weight, highly active polyisobutylene has a number average molecular weight range of 460-5300 g / mol, a molecular weight distribution (PDI) of 1.14-2.66, and an external olefin content of 50%-90% or more.

[0039] The present invention discloses a low molecular weight, highly active polyisobutylene and its preparation method, the beneficial effects of which are as follows:

[0040] (1) More precise and efficient catalytic system regulation: The three-component catalytic system consisting of initiator + aluminum Lewis acid co-initiator + third component forms a "dual regulation switch". Compared with the traditional two-component system, it can more precisely control the chain initiation and chain growth process of polymerization reaction, and can specifically inhibit the formation of internal olefins and significantly improve the selectivity of external olefins. The content of highly active end double bonds is higher, the structure is more controllable, and the molecular weight distribution is relatively narrow.

[0041] (2) Significantly reduce equipment corrosion risk: Select aluminum-based Lewis acids that are less corrosive to equipment, and use ether-based electron donors to complex and regulate acid strength, thereby reducing the damage of highly corrosive reagents to reaction equipment from the source, extending equipment service life and reducing production and maintenance costs.

[0042] (3) Mild reaction conditions and lower energy consumption: No deep low temperature conditions are required. High-activity polymerization can be achieved at -30℃ to 0℃, which greatly reduces the energy consumption of refrigeration and the difficulty of process control, making it more suitable for industrial continuous production.

[0043] (4) High catalytic activity and good process repeatability: The catalytic system has higher activity and stronger stability, significantly improving the reproducibility and batch consistency of the polymerization reaction. While ensuring high selectivity of external olefins, it also takes into account the reaction yield, solving the pain point of "high selectivity accompanied by low yield" in traditional processes. Attached Figure Description

[0044] Figure 1 Test curves of highly active polyisobutylene GPC prepared in Examples 1 and 2.

[0045] Figure 2 Highly active polyisobutylene prepared in Example 2 1 HNMR test curve. Detailed Implementation

[0046] Example 1

[0047] Under nitrogen protection at -10 °C, 5.6 μL (0.04 mmol) of initiator 2-phenylisopropanol, 47 μL (0.512 mmol) of dichloroethyl ether (a third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL of a 25 wt% dichloroethylaluminum n-hexane solution (containing 0.128 mmol of dichloroethylaluminum) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. After washing with water and rotary evaporation to remove unreacted monomers and solvents, the product was dried to obtain the polymer. The calculated yield was 99%. GPC testing was performed, and the curve is shown in the figure below. Figure 1 It is a low molecular weight, highly active polyisobutylene with Mw = 9340 g / mol, Mn = 5247 g / mol, PDI = 1.78, and exo = 85%.

[0048] Example 2

[0049] Under nitrogen protection at -10 °C, a second polymerization method was employed. First, the cryogenic isothermal reactor was replaced with an anhydrous and oxygen-free inert gas environment. In tube 1, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution as the co-initiator was reacted with 47 μL (0.512 mmol) of dichloroethyl ether as the third component to form a complex. Then, 5.6 μL (0.04 mmol) of 2-benzeneisopropanol as the initiator was added. The mixture was aged at the equilibrium temperature of the cryogenic isothermal reactor for 20 min. After the reaction stabilized, the catalytic system from tube 1 was removed and added to tube 2, which contained 2 g of isobutylene and 8 mL of n-hexane, to form a polymerization system for polymerization. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. After washing with water to remove unreacted monomers and solvent, the product was dried to obtain the polymer, with a calculated yield of 71%. GPC testing was performed, and the curve is shown in the figure. Figure 1It is a low molecular weight, highly reactive polyisobutylene, with Mw = 700 g / mol, Mn = 460 g / mol, PDI = 1.52, and exo = 90%. 1 See H NMR spectrum Figure 2 .

[0050] Example 3

[0051] Under nitrogen protection at -10 °C, 5.6 μL (0.04 mmol) of initiator 2-phenylisopropanol, 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.4 mL (0.512 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 98%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 10181 g / mol, Mn = 3825 g / mol, PDI = 2.66, and exo = 50%.

[0052] Example 4

[0053] Under nitrogen protection at -10 °C, 5.5 μL (0.04 mmol) of 1-phenyl-1-propanol (initiator), 64 μL (0.512 mmol) of dibromoethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 71%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 5849 g / mol, Mn = 3997 g / mol, PDI = 1.46, and exo = 72%.

[0054] Example 5

[0055] Under nitrogen protection at -10 °C, 5.5 μL (0.04 mmol) of 1-phenyl-1-propanol (initiator), 64 μL (0.512 mmol) of m-bromoanisole (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 99%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 2958 g / mol, Mn = 1880 g / mol, PDI = 1.57, and exo = 80%.

[0056] Example 6

[0057] Under nitrogen protection at -10 °C, 5.5 μL (0.04 mmol) of 1-phenyl-1-propanol (initiator), 93.5 mg (0.512 mmol) of p-bromoanisole (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 97%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 3817 g / mol, Mn = 2677 g / mol, PDI = 1.42, and exo = 75%.

[0058] Example 7

[0059] Under nitrogen protection at -10 °C, 5.5 μL (0.04 mmol) of 1-phenyl-1-propanol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 84%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 3381 g / mol, Mn = 2133 g / mol, PDI = 1.58, and exo = 74%.

[0060] Example 8

[0061] Under nitrogen protection at -10 °C, 4.67 μL (0.04 mmol) of o-methylbenzyl alcohol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 68%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 7941 g / mol, Mn = 5128 g / mol, PDI = 1.55, and exo = 79%.

[0062] Example 9

[0063] Under nitrogen protection at -10 °C, 4.79 μL (0.04 mmol) of 3-methylbenzyl alcohol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 62%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 3455 g / mol, Mn = 2467 g / mol, PDI = 1.40, and exo = 77%.

[0064] Example 10

[0065] Under nitrogen protection at -10 °C, 4.82 μL (0.04 mmol) of 4-methylbenzyl alcohol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a yield of 81%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 5438 g / mol, Mn = 3498 g / mol, PDI = 1.55, and exo = 80%.

[0066] Example 11

[0067] Under nitrogen protection at -10 °C, 5.37 μL (0.04 mmol) of 1-phenylethanol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a yield of 80%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 2145 g / mol, Mn = 1558 g / mol, PDI = 1.37, and exo = 70%.

[0068] Example 12

[0069] Under nitrogen protection at -10 °C, 5.39 μL (0.04 mmol) of 1-(2-methylphenyl)ethanol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a yield of 85%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 3411 g / mol, Mn = 2599 g / mol, PDI = 1.31, and exo = 82%.

[0070] Example 13

[0071] Under nitrogen protection at -10 °C, 5.4 μL (0.04 mmol) of 1-(4-methylphenyl)ethanol (initiator), 47 μL (0.512 mmol) of dichloroethyl ether (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution (co-initiator) was added to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a calculated yield of 78%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 4461 g / mol, Mn = 3911 g / mol, PDI = 1.14, and exo = 75%.

[0072] Example 14

[0073] Under nitrogen protection at -10 °C, 5.6 μL (0.04 mmol) of initiator 2-phenylisopropanol, 64 μL (0.512 mmol) of dibromoethyl ether (a third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution was added as co-initiator to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. The product was washed with water, and unreacted monomers and solvents were removed by rotary evaporation. After drying, the polymer was obtained with a yield of 90%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 2063 g / mol, Mn = 1772 g / mol, PDI = 1.16, and exo = 76%.

[0074] Example 15

[0075] Under nitrogen protection at -10 °C, 5.6 μL (0.04 mmol) of initiator 2-phenylisopropanol, 33 μL (0.512 mmol) of dioxane (third component), 2 g of isobutylene (IB), and 8 mL of n-hexane were sequentially transferred into a Schlenk tube. After magnetic stirring for 20 min, 0.1 mL (0.128 mmol) of dichloroethylaluminum n-hexane solution was added as co-initiator to initiate the reaction. After stirring for 30 min, 2 mL of anhydrous ethanol was added to terminate the reaction. After washing with water and rotary evaporation to remove unreacted monomers and solvents, the product was dried to obtain the polymer. The yield was calculated to be 97%. GPC analysis showed that it was a low molecular weight, highly reactive polyisobutylene with Mw = 1336 g / mol, Mn = 534 g / mol, PDI = 2.50, and exo = 79%.

[0076] Comparative Example 1

[0077] The difference between Comparative Example 1 and Example 1 is that the amount of co-initiator remains unchanged, the ratio of the third component dichloroethyl ether to the co-initiator changes from 4:1 to 1:1, the conversion rate is 80%, Mw = 2890 g / mol, Mn = 2170 g / mol, PDI = 1.33, and there are almost no external alkenes. This indicates that when the ratio of dichloroethyl ether to EADC is 1:1, a rigid, low nucleophilic counterion is formed, which inhibits β-H elimination. Excess ether loosens the counterion and increases its basicity, selectively abstracting the terminal methyl H to generate external alkenes.

[0078] Comparative Example 2

[0079] The difference between Comparative Example 2 and Example 2 is that the amount of co-initiator remains unchanged, the ratio of the third component dichloroethyl ether to the co-initiator changes from 4:1 to 1:1, the aging time is 10 min, the conversion rate is 78%, Mw = 3040 g / mol, Mn = 2150 g / mol, PDI = 1.41, and there are almost no external olefins. This indicates that when the ratio of dichloroethyl ether to EADC is 1:1, a rigid, low nucleophilic counterion is formed, which inhibits β-H elimination. Excess ether loosens the counterion and increases its basicity, selectively abstracting the terminal methyl H to generate external olefins.

[0080] Comparative Example 3

[0081] The difference between Comparative Example 3 and Example 1 is that without the addition of the third component, the conversion rate was 94%, Mw = 1339 g / mol, Mn = 952 g / mol, PDI = 1.41, and the content of foreign olefins was 0, indicating that the third component can adjust the proportion of foreign olefins.

[0082] Comparative Example 4

[0083] The difference between Comparative Example 4 and Example 1 is that no initiator was added, resulting in a conversion rate of 98%, Mw = 43046 g / mol, Mn = 14015 g / mol, PDI = 3.07, and an external olefin content of 33%. This indicates that dichloroethylaluminum reacts with a very small amount of water in the system, allowing water to act as an initiator. Since this water cannot be completely removed, the experimental reproducibility is poor, and the molecular weight distribution is wide, with a low proportion of external olefins, indicating uncontrolled polymerization.

[0084] Comparative Example 5

[0085] The difference between Comparative Example 5 and Example 1 is that no co-initiator was added, so the conversion rate was 0%, Mw = 0 g / mol, Mn = 0 g / mol, PDI = 0, and the content of foreign olefins was 0, indicating that the co-initiator is a necessary condition for polymerization to occur.

[0086] Comparative Example 6

[0087] The difference between Comparative Example 6 and Example 1 is that neither the initiator nor the third component was added, resulting in a conversion rate of 61%, Mw = 870 g / mol, Mn = 519 g / mol, PDI = 1.67, and an external olefin content of 0, indicating that the co-initiator is a necessary condition for this reaction.

[0088] Comparative Example 7

[0089] The difference between Comparative Example 7 and Example 1 is that ethyl benzoate was used as the initiator, with a yield of 53%, Mw = 7257 g / mol, Mn = 3694 g / mol, and PDI = 1.964. The low yield indicates that the reaction system has problems such as insufficient conversion of raw materials and inactivation of active species.

[0090] Comparative Example 8

[0091] The difference between Comparative Example 8 and Example 1 is that the co-initiator is boron trifluoride, while other parameters remain unchanged. The yield is 47%, Mw = 2011 g / mol, Mn = 1134 g / mol, PDI = 1.77, and exo = 69%. Although there is an external olefin, there is a dangerous HF residue, which makes post-processing troublesome.

[0092] Comparative Example 9

[0093] The difference between Comparative Example 9 and Example 1 is that the co-initiator is titanium tetrachloride, and other parameters remain unchanged. The yield is 71%, Mw = 5119 g / mol, Mn = 1599 g / mol, PDI = 3.20, and exo = 51%. This indicates that TiCl4 has poor end-group selectivity and high Ti residue, which affects product purity and post-processing.

[0094] Comparative Example 10

[0095] The difference between Comparative Example 10 and Example 1 is that the initiator is a C1-C3 alcohol, while methanol is used in this comparative example. With other parameters unchanged, the yield is 68%, Mw = 3112 g / mol, Mn = 1421 g / mol, PDI = 2.19, and exo = 37%. This indicates that 1-phenylisopropanol can form a stable tertiary carbocation, the benzene ring is conjugated to stabilize the positive charge, and there are few chain transfer / side reactions.

[0096] Comparative Example 11

[0097] The difference between Comparative Example 11 and Example 1 is that the initiator is a C1-C3 alcohol, while ethanol is used in this comparative example. With other parameters unchanged, the yield is 44%, Mw = 1991 g / mol, Mn = 912 g / mol, PDI = 2.18, and exo = 44%. This indicates that 1-phenylisopropanol can form a stable tertiary carbocation, and the benzene ring conjugate stabilizes the positive charge, resulting in fewer chain transfer / side reactions.

[0098] Comparative Example 12

[0099] The difference between Comparative Example 12 and Example 1 is that the third component is dichloroethyl ether, while in this comparative example it is diethyl ether. With other components remaining unchanged, the yield is 28%, Mw = 4441 g / mol, Mn = 2551 g / mol, PDI = 1.74, and exo = 44%. This indicates that dichloroethyl ether and dichloroethylaluminum form a moderately strong, dissociable active complex. The active center is not excessively passivated, the polymerization rate is moderate, chain transfer and isomerization are suppressed, and it is closer to controlled polymerization.

Claims

1. A method for preparing low molecular weight, highly reactive polyisobutylene, characterized in that, Using an initiator, a co-initiator, and a third component as a catalytic system, isobutylene is used as a monomer to polymerize low molecular weight, highly active polyisobutylene. The initiator is selected from one or more of the following: 2-phenylisopropanol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol, methylbenzyl alcohol, 1-(2-methylphenyl)ethanol, 1-(4-methylphenyl)ethanol, 1-phenyl-1-propanol, diphenylethanol, 2-hydroxybenzyl alcohol, 4-methoxybenzyl alcohol, 1-(4-methoxyphenyl)ethanol, 2,6-dimethylbenzyl alcohol, 4-tert-butylbenzyl alcohol, 2-phenyl-2-propanol, 2-(p-tolyl)prop-2-ol, 2-(4-methoxyphenyl)prop-2-ol, and 2-(4-chlorophenyl)prop-2-ol. The co-initiator is selected from one or more of the following: trimethylaluminum, triethylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, dichloroethylaluminum, and dichloroisobutylaluminum; The third component is selected from one or more of the following: benzyl methyl ether, benzyl ethyl ether, benzyl phenyl ether, phenyl ethyl ether, dibenzyl ether, dichloroethyl ether, dibromoethyl ether, m-bromoanisole, p-bromoanisole, 4-iodophenylanisole, and dioxane. The molar ratio of the third component to the co-initiator is (1.5~5):1; The prepared low molecular weight, highly active polyisobutylene has a number average molecular weight range of 460-5300 g / mol, a molecular weight distribution of 1.14-2.66, and an external olefin content as high as 50%-90%.

2. The method for preparing low molecular weight, highly active polyisobutylene according to claim 1, characterized in that, The initiator is selected from one or more of 2-phenylisopropanol, 1-phenyl-1-propanol, 4-methylbenzyl alcohol, 1-phenylethanol, 1-(2-methylphenyl)ethanol, and 1-(4-methylphenyl)ethanol; the co-initiator is selected from one or more of dichloroethylaluminum and monochlorodiethylaluminum; and the third component is selected from one or more of dichloroethyl ether, dibromoethyl ether, m-bromoanisole, and p-bromoanisole.

3. The method for preparing low molecular weight, highly reactive polyisobutylene according to claim 1, characterized in that, Specifically, the following steps are included: S1: Material preparation: The polymerization reaction system is an anhydrous and oxygen-free inert gas environment. The solvent, isobutylene monomer, initiator, co-initiator and third component after dehydration and deoxygenation are all stored in an inert environment. S2: Aggregation: Choose one of the following two polymerization methods: The first method involves adding an initiator to a low-temperature isothermal reactor to replace it with an anhydrous and oxygen-free inert gas environment, adding a third component, an organic solvent, and isobutylene monomer, stirring until homogeneous, and obtaining a polymerization system. A co-initiator is then added to initiate the polymerization reaction. After polymerization, a terminator is added to terminate the reaction and obtain the polymerization product. The second method: First, replace the low-temperature constant temperature reactor with an anhydrous and oxygen-free inert gas environment, react the co-initiator and the third component to form a complex, then add the initiator, stir evenly, and after stabilization, take out the catalytic system and add it to a solution containing isobutylene monomer to form a polymerization system for catalytic polymerization. After the polymerization is completed, add a terminator to terminate the polymerization and obtain the polymerization product. S3: Post-processing: The polymerization product was washed with deionized water to remove unreacted isobutylene monomers and organic solvents, and then dried to obtain low molecular weight, highly active polyisobutylene with a yield of 62-99%.

4. The method for preparing low molecular weight, highly active polyisobutylene according to claim 3, characterized in that, In S1, the organic solvent is selected from one or more of the following: n-hexane, tetrahydrofuran, chloromethane, dichloromethane, toluene, chloroethane, vinyl chloride, and propane.

5. The method for preparing low molecular weight, highly active polyisobutylene according to claim 3, characterized in that, The inert gas is nitrogen or argon.

6. The method for preparing low molecular weight, highly active polyisobutylene according to claim 3, characterized in that, In the polymerization system, the mass concentration of isobutylene monomer is 5~50wt%; the molar ratio of initiator to co-initiator is (0.01~1):1; the mass percentage of co-initiator to monomer is 0.02~10wt%; the reaction temperature is -30~0℃; and the polymerization time is 5~60min.

7. The method for preparing low molecular weight, highly active polyisobutylene according to claim 3, characterized in that, The co-initiator is added as follows: when there is only one co-initiator, it should be added slowly at a rate of 0.5-2 mL / min; when there are two or more co-initiators, the two co-initiators should be added slowly in sequence at intervals of 0-45 min at a rate of 0.5-2 mL / min.

8. The method for preparing low molecular weight, highly active polyisobutylene according to claim 3, characterized in that, The terminator is selected from water, anhydrous methanol, anhydrous ethanol, or an ethanol / water mixed solution containing 1 wt% NaOH; in the ethanol / water mixed solution, the volume ratio of ethanol to water is 1:1; the amount of terminator accounts for 1~5% of the volume percentage of the polymerization system.

9. The method for preparing low molecular weight, highly active polyisobutylene according to claim 3, characterized in that, In step S3, the method for removing unreacted isobutylene monomer and organic solvent is vacuum evaporation; the drying process parameters are: pressure 0.1 MPa, drying at 40~80℃ to constant weight.

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