Process for the preparation of polar polyolefins in aqueous media and polar polyolefins obtained by the process

Abstract

The present application relates to the field of polyolefins, in particular to a method for preparing polar polyolefins in aqueous medium and polar polyolefins obtained by the method. The method for preparing polar polyolefins provided by the present application uses water as a polymerization solvent to prepare high molecular weight polar polyolefins by coordination polymerization, which is the first time to realize the preparation of high molecular weight polar polyolefins by aqueous coordination polymerization. Water replaces the traditional organic solvent as the polymerization reaction medium, which is environmentally friendly. The obtained polymer is in the form of uniform nanoparticles, has regular morphology, and is easy to separate from the stirring paddle of the reaction kettle. Experiments show that the phosphine nickel catalyst used in the present application catalyzes the aqueous polymerization of ethylene and polar monomers to obtain linear polar functionalized polyethylene with good performance. The insertion of polar monomers improves the surface properties of the polymer while maintaining the mechanical properties, which is beneficial to the processing and use of polyolefin materials.

Description

Technical Field

[0001] This invention relates to the field of polyolefins, specifically to a method for preparing polar polyolefins in an aqueous medium and the polar polyolefins obtained by the method. Background Technology

[0002] Since Ziegler and Natal's pioneering work in the early 1950s, the field of polyolefins has achieved tremendous success in both academia and industry. Polyolefin materials, with their low price and excellent performance, have become the most produced and widely used polymer materials, applied in plastics products, packaging materials, construction, agriculture, and other industries, with a current global annual production approaching 200 million tons. Because polyolefin molecules contain only carbon-hydrogen bonds and carbon-carbon bonds, lacking polar functional groups, the bonds in polyolefin molecules only undergo van der Waals interactions, making polyolefins nonpolar molecules, which also contributes to their stable chemical properties. However, this also creates some difficulties in processing polyolefins, such as poor flowability and poor compatibility. One way to improve the processing properties of polyolefins is to introduce polar functional groups into the originally nonpolar olefin chain. This can significantly improve the polymer's adhesion, flexibility, solvent resistance, rheological properties, and compatibility with other polymers and polymeric additives. In industry, this reduces processing difficulties and improves the material properties of polyolefins. Therefore, polar polyolefins are a high-end polyolefin material.

[0003] The transition metal-catalyzed coordination copolymerization of ethylene and polar monomers can achieve the direct synthesis of polar functionalized polyolefins, and has the advantages of controllable product microstructure and fewer side reactions such as degradation and crosslinking, thus attracting widespread attention. Currently, the copolymerization reaction of polar monomers and ethylene is carried out in organic solvents, such as toluene and hexane, which easily causes environmental pollution; the polymer in the solvent requires a large amount of ethanol to settle, which is not conducive to reducing production costs and adds cumbersome procedures. If water can be used as the polymerization solvent, the above problems can be solved well. The advantages of polymerization in water are as follows: (1) From the perspective of environment and safety, water is an ideal suspension medium, which will not put too much pressure on the environment and reduce production costs, and is an environmentally friendly alternative to products containing organic solvents; (2) Since water has a very high heat capacity, it can be safely used as a continuous phase or solvent, which is beneficial for polymerization reactions with a large amount of exothermic heat; (3) Ethylene emulsion polymerization with water as the continuous phase can produce polymer nanoparticles with high conversion rate, regular morphology, and easy separation, reducing the problem of polyethylene sticking to the reactor in homogeneous polymerization, which is beneficial to the maintenance of polymerization equipment.

[0004] However, the toxic effects of water on most non-radical reactive substances (anions, cations, and organometallic substances) limit its applications almost entirely to traditional free radical chemistry. Due to the low oxyphilicity of post-transition metal complexes, they are generally highly resistant to polar media. As early as 2000, there was work on post-transition metal-catalyzed polymerization in water (Macromolecules 2001, 34, 2022–2026). More recently, Stefan Mecking's group at the University of Konstanz, Germany, achieved homopolymerization of ethylene in the aqueous phase using phosphonol catalysts (J. Am. Chem. Soc. 2021, 143, 20605-20608; Angew. Chem. Int. Ed. 2022, 61, e202203923). The gap between emulsion and organometallic chemistry is rapidly being bridged. Commercially available polyethylene emulsion products are already available, commonly used in coatings, modifiers, etc. However, commercially viable polyolefin aqueous dispersions can only be produced through secondary dispersion technology, which significantly increases production costs and process steps compared to polyethylene emulsions formed directly in the aqueous phase. Furthermore, a method for producing polar polyolefin aqueous dispersions has never been developed, preventing the widespread application of the unique material properties of polar polyolefins in olefin emulsion products. This is because the preparation of polar polyolefins through coordination copolymerization of olefins and polar monomers in water is extremely challenging. Although olefin coordination polymerization has been developed for 70 years, and there are numerous reports on the coordination copolymerization of olefins and polar monomers in organic solvents, this reaction in water is extremely difficult to achieve. To date, only two papers have reported the generation of low molecular weight (less than 15,000) polar polyolefins in the aqueous phase (Macromolecules 2002, 35, 1513-1523; Macromolecules 2009, 42, 6953-6963); the low molecular weight characteristic makes the materials difficult to apply. To date, no breakthrough has been achieved in the coordination copolymerization of olefins and polar monomers in water to prepare high molecular weight polar polyolefins. There has never been a production method for high molecular weight polar polyolefin aqueous dispersions, which makes it impossible to widely apply the unique material properties of polar polyolefins in olefin emulsion products. Therefore, the preparation of polar polyolefins by coordination copolymerization of olefins and polar monomers in water is extremely challenging. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing polar polyolefins in an aqueous medium and the polar polyolefins obtained by the method. The preparation method provided by the present invention can realize the coordination copolymerization of ethylene and polar monomers in an aqueous medium to obtain highly active, high molecular weight, and adjustable polar monomer insertion rate aqueous dispersion polar polyolefins.

[0006] This invention provides a method for preparing polar polyolefins in an aqueous medium, comprising the following steps:

[0007] Under the action of a phosphonophenol-nickel catalyst, ethylene and polar monomers are polymerized in an aqueous medium to obtain polar polyolefins;

[0008] The phosphonol nickel catalyst has the structure of formula I:

[0009]

[0010] The L1, L2, L3, and L4 are independently selected from hydrogen or C4 to C4. 10 tertiary alkyl groups;

[0011] R1 and R2 are independently selected from C1 to C2. 20 hydrocarbon groups, C1-C 20 heterohydrocarbon groups, C1-C 20 Hydrocarbon-substituted phosphine groups or C1-C1 groups 20 Phosphine groups substituted with heteroalkyl groups;

[0012] R3 and R4 are independently selected from C4 to C5. 10 Tertiary alkyl groups or groups with the structure shown in Formula II;

[0013]

[0014] R5, R6 and R7 are independently selected from hydrogen, trihaloalkyl, and alkyloxy groups;

[0015] The sum of the number of trihaloalkyl groups in R3 and R4 does not exceed one.

[0016] The inventors of this application have creatively discovered that the above-mentioned phosphonophenol nickel catalyst, when applied to the preparation of polar polyolefins, can catalyze the coordination copolymerization of ethylene and polar monomers in an aqueous medium to obtain highly active, high molecular weight, and tunable polar monomer insertion rate aqueous dispersion polar polyolefins.

[0017] The aqueous medium of this invention comprises an aqueous phase, an oil phase, an emulsifier, and a pH adjuster; the volume percentage of the aqueous phase in the aqueous and oil phases exceeds 90%. Specifically, the aqueous medium comprises an aqueous phase, an oil phase, and a co-emulsifier in a volume ratio of 100:(1-10):(0-5), preferably 100:(1-10):(1-5); the concentration of the emulsifier in the aqueous medium is 0.3-0.1 mol / L, preferably 0.2 mol / L; the concentration of the pH adjuster in the aqueous medium is 0.3-0.1 mol / L, preferably 0.2 mol / L. The aqueous phase of this invention is specifically degassed deionized water; the oil phase is selected from at least one of toluene, hexane, or dichloromethane; the emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, calcium dodecylbenzene sulfonate, or sodium stearate; the pH adjuster is selected from at least one of sodium hydroxide, potassium hydroxide, or calcium hydroxide; and the co-emulsifier is selected from at least one of n-hexanol, cyclohexanol, cetyl alcohol, or octadecyl alcohol.

[0018] In the phosphonophenol nickel catalyst of the present invention, L1, L2, L3 and L4 are independently selected from hydrogen or C4-C4. 10 The tertiary alkyl group; specifically, L1, L2, L3, and L4 are independently selected from hydrogen or tert-butyl. In some embodiments of the invention, L1 is selected from tert-butyl, and L2, L3, and L4 are all selected from hydrogen. R1 and R2 are independently selected from C1 to C2. 20 hydrocarbon groups, C1-C 20 heterohydrocarbon groups, C1-C 20 Hydrocarbon-substituted phosphine groups or C1-C1 groups 20 The phosphine group is substituted with a heteroalkyl group; specifically, R1 and R2 are independently selected from C1 to C2. 20 Alkyl groups, C1-C 20 heteroaryl, C1-C 20 aryl-substituted phosphine or C1-C 20 The phosphine group is a heteroaryl-substituted group; more specifically, R1 and R2 are independently selected from -PPh3, -Ph, -Py, or -Me, wherein -PPh3 is triphenylphosphine, -Ph is phenyl, -Py is pyridyl, and -Me is methyl. In some embodiments of the invention, R1 and R2 are independently selected from -PPh3 or -Ph, and R1 and R2 are not the same. In other embodiments of the invention, R1 and R2 are independently selected from -Py or -Me, and R1 and R2 are not the same.

[0019] In the phosphonophenol nickel catalyst of the present invention, R3 and R4 are independently selected from C4 to C5. 10The group is a tertiary alkyl group or a group with the structure shown in Formula II; specifically, R3 and R4 are independently selected from tert-butyl groups or groups with the structure shown in Formula II. In the group with the structure shown in Formula II, R5, R6 and R7 are independently selected from hydrogen, trihaloalkyl, and alkyloxy groups, wherein the trihaloalkyl group is selected from trifluoromethyl, trichloromethyl or tribromomethyl, and the alkyloxy group is selected from methoxy, cyclohexenoxy, isopropoxy or aromaticoxy groups.

[0020] If the R3 and R4 groups in the phosphonophenol nickel catalyst of this invention have excessively large electron-withdrawing effects, it will inhibit the activity of the phosphonophenol nickel catalyst in ethylene polymerization. In the phosphonophenol nickel catalyst of this invention, the sum of the number of trihaloalkyl groups in R3 and R4 does not exceed one.

[0021] If the steric hindrance effect of the R3 and R4 groups in the phosphonophenol nickel catalyst of this invention is too small, it will also inhibit the activity of the phosphonophenol nickel catalyst in ethylene polymerization, especially in the polymerization of ethylene and polar monomers in an aqueous medium. In the phosphonophenol nickel catalyst of this invention, R3 and R4 are not simultaneously selected from C4 to C6. 10 Tertiary alkyl groups; when R5, R6 and R7 are all selected from hydrogen, R3 and R4 are not the same.

[0022] In some embodiments of the present invention, the phosphonophenol nickel catalyst of the present invention has a structure of formula Ni2, Ni4, Ni5, Ni6, Ni7 or Ni8:

[0023]

[0024] In this invention, -tBu is tert-butyl, -Cy is cyclohexenyl, and -iPr is isopropyl.

[0025] The structure of the polar monomer described in this invention is shown in Formula III:

[0026]

[0027] n is an integer greater than or equal to 1;

[0028] The G is selected from hydroxyl, halogen, cyano, C1-C5 alkyl-substituted ester, C1-C5 alkyl-substituted acyloxy, C1-C5 alkyl-substituted acyl, C1-C5 alkyl-substituted ether, C1-C5 alkyl-substituted amide, C1-C5 alkyl-substituted sulfone, C6-C5 alkyl-substituted acyl, C6 ... 12 Aryl-substituted sulfones, C6-C 12 One of the aryl-substituted sulfoxide groups. Specifically, the halogen group is selected from F, Cl, or Br; the C1-C5 alkyl group is selected from methyl, ethyl, propyl, or butyl; the C6-C5 alkyl group is selected from C4-C5 methyl, C6-C6 methyl, C7-C6 alkyl ... 12 The aryl group is selected from phenyl.

[0029] In some embodiments of the present invention, the structure of the polar monomer is shown in Formulas 1 to 18:

[0030]

[0031] This invention utilizes a nickel phosphonate catalyst to polymerize ethylene and a polar monomer in an aqueous medium to obtain a polar polyolefin. Specifically, under a protective gas atmosphere, the nickel phosphonate catalyst and the polar monomer are mixed in an aqueous medium, and ethylene is introduced to carry out the polymerization reaction to obtain a polar polyolefin. More specifically, under a protective gas atmosphere, an emulsifier and an aqueous phase are mixed, and a mixed solution of a co-emulsifier, a polar monomer, an oil phase, and the nickel phosphonate catalyst is added, followed by the introduction of ethylene to carry out the polymerization reaction to obtain a polar polyolefin. The protective gas used in this invention is a protective gas well-known to those skilled in the art, such as nitrogen, helium, neon, or argon.

[0032] The olefin described in this invention is reacted at a pressure of 20 bar to 40 bar, preferably 20 bar; the polar monomer is used in the aqueous medium at a concentration of 0.1 mol / L to 1 mol / L; and the phosphonophenol-nickel catalyst has a molar mass of 1 × 10⁻⁶ in the aqueous medium. -4 mol / L~5×10 -5 mol / L. The polymerization reaction described in this invention is carried out at 500–1000 r / min, preferably at 900 r / min. The temperature of the polymerization reaction described in this invention is 30–70 °C, preferably 50 °C; the time is 30–60 min, preferably 60 min.

[0033] This invention also provides polar polyolefins obtained by the above preparation method. The polar polyolefins obtained by this invention exhibit high activity and high molecular weight, with the highest activity reaching 11.8 × 10⁻⁶. 3 mol PE .mol Ni -1 h -1 It has a maximum molecular weight of 539 kDa, and can also achieve a high polar monomer insertion rate while maintaining a high molecular weight.

[0034] This invention provides a method for preparing polar polyolefins in an aqueous medium. The method yields polar polyolefins that, using water as the polymerization solvent, produce high molecular weight polar polyolefins through coordination copolymerization. This is the first time that high molecular weight polar polyolefins have been obtained through aqueous coordination copolymerization. Water replaces traditional organic solvents as the polymerization reaction medium, making it environmentally friendly. Furthermore, the resulting polymer exhibits uniform nanoparticles with regular morphology, facilitating separation from the reactor's agitator. This invention utilizes the aforementioned phosphonol nickel catalyst to achieve highly active, high molecular weight coordination copolymerization of ethylene with various polar monomers in an aqueous medium at 20 bar and 50°C. The phosphonol nickel catalyst used possesses high activity and high polymerization molecular weight, requiring no co-catalyst during application, and exhibits high tolerance to water solvent and various polar monomers. Its application in the preparation of polar polyolefins enables the production of highly active, high molecular weight aqueous dispersions of polar polyolefins with adjustable polar monomer insertion rates in an aqueous phase. Experiments show that using the phosphonophenol nickel catalyst of this invention to catalyze the aqueous polymerization of ethylene and polar monomers yields high-performance linear polar functionalized polyethylene. The insertion of polar monomers improves the surface properties of the polymer while maintaining its mechanical properties, which is beneficial for the processing and use of polyolefin materials. Attached Figure Description

[0035] Figure 1 The 1H NMR spectrum of the polar polyolefin in Example 32;

[0036] Figure 2 This is a GPC test chart of the polar polyolefin in Example 32;

[0037] Figure 3 The 1H NMR spectrum of the polar polyolefin in Example 33;

[0038] Figure 4 This is a GPC test chart of the polar polyolefin in Example 33;

[0039] Figure 5 The 1H NMR spectrum of the polar polyolefin in Example 34;

[0040] Figure 6 The image shows the DSC test results of the polar polyolefin in Example 32.

[0041] Figure 7 The image shows the DSC test results of the polar polyolefin in Example 33.

[0042] Figure 8 This is a DSC test chart of the polar polyolefin in Example 34. Detailed Implementation

[0043] This invention discloses a method for preparing polar polyolefins in an aqueous medium. The polar polyolefins obtained by this method can be achieved by appropriately modifying the process parameters based on the content of this document. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art will clearly be able to modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0044] The method for preparing high molecular weight polar polyolefins in an aqueous medium according to the present invention includes: using degassed deionized water as a polymerization solvent, specifically, the composition of the polymerization solvent is water:n-hexanol:toluene = 100:3:1, wherein water serves as the aqueous phase in the emulsion, toluene serves as the oil phase in the emulsion, and n-hexanol serves as a co-emulsifier; adding 0.2 mol / L sodium dodecyl sulfate as an emulsifier to the polymerization solvent, adding 0.2 mol / L NaOH to create an alkaline environment, and forming an emulsion by rapid stirring, typically at 500 r / min to 1000 r / min; then introducing a certain amount of polar monomer and adding an appropriate amount of catalyst, and carrying out coordination polymerization at a specific temperature to obtain polar functionalized polyethylene. By controlling the polar monomer feed ratio, the molecular weight of the copolymer and the polar monomer insertion rate can be controlled.

[0045] The present invention will be further described below with reference to the embodiments:

[0046] Examples 1-6

[0047] The phosphonophenol nickel catalysts Ni2 and Ni4 to Ni8 prepared in this invention have the following structural formulas:

[0048]

[0049] The Ni2 and Ni4-Ni8 catalysts prepared above were used to carry out aqueous phase ethylene homopolymerization reactions as Examples 1-6 of the present invention to test their catalytic performance. The specific steps are as follows:

[0050] First, the steel reactor connected to the gas pipeline was vacuum dried at 100°C for at least 1 hour. Then, the temperature was adjusted to 50°C. A 150 mL Schlenk reaction flask was dried in a vacuum oven for at least 1 hour, then vacuum cooled to room temperature and placed in a glove box. In the glove box, 1 g of NaOH and 6 g of sodium dodecyl sulfate were weighed, and 100 mL of degassed deionized water was injected under a nitrogen atmosphere, stirring for 5 minutes to dissolve. An appropriate amount of catalyst was weighed and dissolved in 1 mL of toluene, and 3 mL of n-hexanol was injected into the Schlenk flask using a syringe and stirred for 1 minute. Under a nitrogen atmosphere, the mixture was injected into the steel reactor. With rapid stirring (900 rpm), the reaction gas was introduced and maintained at 20 bar. After a specific time, the reactor pressure was released, 200 mL of anhydrous ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried in a vacuum oven to constant weight.

[0051] Table 1 shows the Ni2 and Ni4-Ni8 catalysts, their dosages, and the yields of the resulting products. The weight-average molecular weight M of the polymer was obtained by GPC analysis. w and M w / M n The melting points of the polymers were obtained by DSC testing, as shown in Table 1. All data in Table 1 are based on results from at least two parallel experiments (unless otherwise stated). M w M is the weight-average molecular weight. w / M n The polymer dispersibility index is determined by GPC in 1,2,4-trichlorobenzene at 160°C, relative to a polystyrene standard.

[0052] Table 1

[0053]

[0054] Comparative Examples 1-2

[0055] The phosphonophenol nickel catalysts Ni1 and Ni3 described in this invention have the following structural formulas:

[0056]

[0057] The Ni1 and Ni3 catalysts prepared above were used to carry out aqueous phase ethylene homopolymerization reaction as comparative examples 1 and 2 of the present invention to test their catalytic performance. The specific steps were the same as those in Examples 1 to 6, and will not be repeated here.

[0058] Table 2 shows the Ni1 and Ni3 catalysts, their dosages, and the yields of the resulting products. The weight-average molecular weight M of the polymer was obtained by GPC analysis. w and M w / M nThe melting points of the polymers were obtained by DSC testing, as shown in Table 2. All data in Table 2 are based on results from at least two parallel experiments (unless otherwise stated). Mw is the weight-average molecular weight, and Mw / Mn is the polymer dispersibility index, determined by GPC at 160 °C in 1,2,4-trichlorobenzene, relative to polystyrene standards.

[0059] Table 2

[0060]

[0061] As shown in Tables 1 and 2, the catalysts Ni1 to Ni8 prepared in this invention exhibit good homopolymerization effects in aqueous ethylene, except for Ni1 and Ni3. Ni1, however, cannot produce polyethylene and is therefore unsuitable for aqueous ethylene homopolymerization, lacking polymerization activity in the copolymerization of polar monomers. Ni3, as a catalyst, fails to achieve the required high molecular weight, resulting in a waxy polymer. Further testing is needed for Ni2, Ni4, Ni5, Ni6, Ni7, and Ni8 to verify their catalytic effects in the preparation of aqueous polar polyolefins, as good homopolymerization effects in aqueous ethylene are not necessarily correlated with good preparation effects in aqueous polar polyolefins.

[0062] Examples 7-43

[0063] The high molecular weight polar polyolefins of this invention were prepared using catalysts Ni2, Ni4, Ni5, Ni6, Ni7, and Ni8, yielding the polar polyolefins of Examples 7-43. The specific steps are as follows:

[0064] First, the steel reactor connected to the gas pipeline was vacuum dried at 100°C for at least 1 hour, then the temperature was adjusted to 50°C. Under an inert gas atmosphere, a 150 mL Schlenk reaction flask was dried in a vacuum oven for at least 1 hour, then vacuum cooled to room temperature. In a glove box, 1 g of NaOH and 6 g of sodium dodecyl sulfate were weighed out, and 96 mL of degassed deionized water was injected under a nitrogen atmosphere, stirring for 5 minutes to dissolve. 3 mL of n-hexanol, an appropriate amount of the required monomer, and an appropriate amount of catalyst were weighed and dissolved in 1 mL of toluene. These were then injected sequentially into the Schlenk flask using a syringe, stirring for 1 minute. Under a nitrogen atmosphere, the mixture was injected into the steel reactor. With rapid stirring at 900 rpm, the reaction gas was introduced and maintained at 20 bar. Polymerization was terminated after 1 hour. The reactor pressure was released, and 200 mL of anhydrous ethanol was added to quench the polymerization reaction. The polymer was filtered and dried to constant weight in a vacuum oven. The catalysts used in Examples 7-43 and their amounts, the polar monomers and their amounts, and the yields and activities of the obtained polar polyolefins are shown in Table 3.

[0065] The polar monomer insertion rate of the polar polyolefin was calculated by proton NMR spectroscopy of the copolymer, and the weight-average molecular weight M of the polymer was obtained by GPC testing. w and M w / M n The melting points of the polymers were obtained by DSC testing, as shown in Table 3. All data in Table 3 are based on results from at least two parallel experiments (unless otherwise stated). Mw is the weight-average molecular weight, and Mw / Mn is the polymer dispersibility index, determined by GPC at 160 °C in 1,2,4-trichlorobenzene, relative to polystyrene standards.

[0066] Table 3

[0067]

[0068]

[0069] Examples 7-43 above list the 1H NMR and GPC test data for Examples 32, 33, and 34, such as... Figures 1-6 As shown, Figure 1 The above is the 1H NMR spectrum of the polar polyolefin from Example 32. Figure 2 This is a GPC test chart of the polar polyolefin in Example 32. Figure 3 The above is the 1H NMR spectrum of the polar polyolefin in Example 33. Figure 4 This is a GPC test chart of the polar polyolefin in Example 33. Figure 5 The above is the 1H NMR spectrum of the polar polyolefin in Example 34. Figure 6 This is the DSC test result of the polar polyolefin in Example 32. Figure 7 This is the DSC test result of the polar polyolefin in Example 33. Figure 8 This is a DSC test chart of the polar polyolefin in Example 34.

[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing polar polyolefins in an aqueous medium, characterized in that, Includes the following steps: Under the action of a phosphonophenol-nickel catalyst, ethylene and polar monomers are polymerized in an aqueous medium to obtain polar polyolefins; The aqueous medium includes an aqueous phase, an oil phase, an emulsifier, a co-emulsifier, and a pH adjuster; The aqueous phase accounts for more than 90% of the volume of the aqueous and oil phases. The volume ratio of the aqueous phase, oil phase, and co-emulsifier is 100:(1~10):(0~5); The concentration of the emulsifier in the aqueous medium is 0.3~0.1 mol / L; The concentration of the pH adjuster in the aqueous medium is 0.3~0.1 mol / L; The phosphonol nickel catalyst has the structure of formula I: Equation I; The L1, L2, L3, and L4 are independently selected from hydrogen or C4~C 10 tertiary alkyl groups; R1 and R2 are independently selected from -PPh3, -Ph, -Py, or -Me; R3 and R4 are independently selected from C4~C 10 Tertiary alkyl groups or groups with the structure shown in Formula II; Formula II; R5, R6 and R7 are independently selected from hydrogen, trihaloalkyl, and alkyloxy groups; The sum of the number of trihaloalkyl groups in R3 and R4 does not exceed 1; The structure of the polar monomer is shown in Formula III: Formula III; The n is an integer from 1 to 8; The G is selected from hydroxyl, halogen, cyano, C1-C5 alkyl-substituted ester, C1-C5 alkyl-substituted acyloxy, C1-C5 alkyl-substituted acyl, C1-C5 alkyl-substituted ether, C1-C5 alkyl-substituted amide, C1-C5 alkyl-substituted sulfone, C6-C 12 aryl-substituted sulfones, C6~C 12 One of the aryl-substituted sulfoxide groups.

2. The preparation method according to claim 1, characterized in that, R3 and R4 are not simultaneously selected from C4~C 10 tertiary alkyl groups; When R5, R6, and R7 are all selected from hydrogen, R3 and R4 are not the same.

3. The preparation method according to claim 1, characterized in that, L1, L2, L3 and L4 are independently selected from hydrogen or tert-butyl; R1 and R2 are independently selected from -PPh3, -Ph, -Py, or -Me; R3 and R4 are independently selected from tert-butyl groups or groups with the structure shown in Formula II; R5, R6 and R7 are independently selected from hydrogen, trifluoromethyl, methoxy, cyclohexenoxy, isopropoxy or aromatic oxy.

4. The preparation method according to claim 1, characterized in that, The phosphonol nickel catalyst has a structure of formula Ni2, Ni4, Ni5, Ni6, Ni7, or Ni8: Formula Ni2; Formula Ni4; Formula Ni5; Formula Ni6; Formula Ni7; Formula Ni8.

5. The preparation method according to claim 1, characterized in that, The structures of the polar monomers are shown in Formulas 1 to 18: Formula 1; Formula 2; Formula 3; Equation 4; Formula 5; Formula 6; Formula 7; Formula 8; Equation 9; Formula 10; Formula 11; Equation 12; Equation 13; Equation 14; Formula 15; Formula 16; Equation 17; Formula 18.

6. The preparation method according to claim 1, characterized in that, The pressure of the ethylene in the reaction system is 20 bar to 40 bar; The concentration of the polar monomer in the aqueous medium is 0.1 mol / L to 1 mol / L; The concentration of the nickel phosphonate catalyst in the aqueous medium is 1×10⁻⁶. -4 mol / L ~ 5×10 -5 mol / L.

7. The polar polyolefin obtained by any of the preparation methods described in claims 1 to 6.

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