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METHOD FOR PREPARING POLYMER, AND OBTAINED POLYMER

20240228680 ยท 2024-07-11

    Inventors

    Cpc classification

    International classification

    Abstract

    A method for preparing polymer includes the steps of enabling olefin and unsaturated carboxylate be subjected to a polymerization reaction in the presence of a catalyst to generate an olefin-unsaturated carboxylate polymer. The catalyst has a primary catalyst and optionally a cocatalyst. The primary catalyst has at least one complex represented by formula I, formula I, or formula I. By selecting a reacted unsaturated carboxylate monomer, catalysts, and a suitable polymerization process, a spherical and/or sphere-like polymer having good shape is directly prepared without subsequent processing steps such as granulation, and the obtained polymer product is not prone to fouling in a reactor and is convenient for transportation.

    ##STR00001##

    Claims

    1. A method for preparing a polymer, comprising polymerizing an olefin and an unsaturated carboxylic ester in the presence of a catalyst to form an olefin-unsaturated carboxylic ester polymer, wherein the catalyst comprises a main catalyst and optionally a cocatalyst, the main catalyst being at least one selected from the group consisting of: the diimine-metal complexes represented by formula I: ##STR00032## wherein, R.sub.1 and R.sub.2 are each independently a C1-C30 hydrocarbyl with or without a substituent; R.sub.5-R.sub.8 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, and C1-C20 hydrocarbyl with or without a substituent, and two or more of R.sub.5-R.sub.8 groups are optionally joined to form a ring; each R.sub.12 is independently a C1-C20 hydrocarbyl with or without a substituent; each Y is independently a Group VIA nonmetal atom; each M is independently a Group VIII metal; and each X is independently selected from the group consisting of halogen, C1-C10 hydrocarbyl with or without a substituent and C1-C10 hydrocarbyloxy with or without a substituent, the aminoimine-metal complexes represented by formula I: ##STR00033## wherein, R.sub.1 and R.sub.2 are each independently a C1-C30 hydrocarbyl with or without a substituent; each R.sub.3 is independently selected from the group consisting of hydrogen and C1-C20 hydrocarbyl with or without a substituent; R.sub.5-R.sub.8 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, and C1-C20 hydrocarbyl with or without a substituent, and two or more of R.sub.5-R.sub.8 groups are optionally joined to form a ring; each R.sub.12 is independently a C1-C20 hydrocarbyl with or without a substituent; each Y is independently a Group VIA non-metal atom; each M is independently a Group VIII metal; and each X is independently selected from the group consisting of halogen, C1-C10 hydrocarbyl with or without a substituent and C1-C10 hydrocarbyloxy with or without a substituent, and the diimine-metal complexes represented by formula I: ##STR00034## wherein, R.sub.1 and R.sub.2 are each independently a C1-C30 hydrocarbyl with or without a substituent; R.sub.5-R.sub.7 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, and C1-C20 hydrocarbyl with or without a substituent, and two or more of R.sub.5-R.sub.7 groups are optionally joined to form a ring; each R.sub.11 is independently a C1-C20 hydrocarbyl with or without a substituent; each Y is independently a Group VIA non-metal atom; each M is independently a Group VIII metal; and each X is independently selected from the group consisting of halogen, C1-C10 hydrocarbyl with or without a substituent and C1-C10 hydrocarbyloxy with or without a substituent.

    2. The method as claimed in claim 1, having at least one of the following features: R.sub.1 and R.sub.2 are independently selected from the group consisting of C1-C20 alkyl with or without a substituent and C6-C20 aryl with or without a substituent, and preferably R.sub.1 and/or R.sub.2 are/is a group represented by formula A: ##STR00035## wherein, R.sup.1-R.sup.5 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C20 alkyl with or without a substituent, C2-C20 alkenyl with or without a substituent, C2-C20 alkynyl with or without a substituent, C3-C20 cycloalkyl with or without a substituent, C1-C20 alkoxy with or without a substituent, C2-C20 alkenoxy with or without a substituent, C2-C20 alkynoxy with or without a substituent, C3-C20 cycloalkoxy with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent, and C7-C20 alkaryl with or without a substituent, and two or more of R.sup.1-R.sup.5 groups are optionally joined to form a ring; preferably, wherein R.sup.1-R.sup.5 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C10 alkyl with or without a substituent, C2-C10 alkenyl with or without a substituent, C2-C10 alkynyl with or without a substituent, C3-C10 cycloalkyl with or without a substituent, C1-C10 alkoxy with or without a substituent, C2-C10 alkenoxy with or without a substituent, C2-C10 alkynoxy with or without a substituent, C3-C10 cycloalkoxy with or without a substituent, C6-C15 aryl with or without a substituent, C7-C15 aralkyl with or without a substituent, and C7-C15 alkaryl with or without a substituent; each M is independently selected from the group consisting of nickel and palladium; each Y is independently selected from the group consisting of O and S; each X is independently selected from the group consisting of halogen, C1-C10 alkyl with or without a substituent and C1-C10 alkoxy with or without a substituent, and preferably from the group consisting of halogen, C1-C6 alkyl with or without a substituent and C1-C6 alkoxy with or without a substituent; each R.sub.11 is independently a C1-C20 alkyl with or without a substituent, preferably a C1-C10 alkyl with or without a substituent, and more preferably a C1-C6 alkyl with or without a substituent; each R.sub.12 is independently a C1-C20 alkyl with or without a substituent, preferably a C1-C10 alkyl with or without a substituent, and more preferably a C1-C6 alkyl with or without a substituent; each R.sub.3 is independently selected from the group consisting of C1-C20 alkyl with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent and C7-C20 alkaryl with or without a substituent; preferably, each R.sub.3 is independently selected from the group consisting of C1-C10 alkyl with or without a substituent, C6-C10 aryl with or without a substituent, C7-C15 aralkyl with or without a substituent and C7-C15 alkaryl with or without a substituent; and more preferably, each R.sub.3 is a C1-C6 alkyl with or without a substituent, preferably methyl, ethyl, propyl or butyl.

    3. The method as claimed in claim 1, wherein the main catalyst comprises at least one complex selected from the group consisting of: the diimine-metal complexes represented by a formula III: ##STR00036## wherein, R.sup.1-R.sup.11 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C20 alkyl with or without a substituent, C2-C20 alkenyl with or without a substituent, C2-C20 alkynyl with or without a substituent, C3-C20 cycloalkyl with or without a substituent, C1-C20 alkoxy with or without a substituent, C2-C20 alkenoxy with or without a substituent, C2-C20 alkynoxy with or without a substituent, C3-C20 cycloalkoxy with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent, and C7-C20 alkaryl with or without a substituent; and M, X, Y and R.sub.12 are as defined for the Formula I, the aminoimine-metal complexes represented by a formula III: ##STR00037## wherein, R.sup.1-R.sup.11 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C20 alkyl with or without a substituent, C2-C20 alkenyl with or without a substituent, C2-C20 alkynyl with or without a substituent, C3-C20 cycloalkyl with or without a substituent, C1-C20 alkoxy with or without a substituent, C2-C20 alkenoxy with or without a substituent, C2-C20 alkynoxy with or without a substituent, C3-C20 cycloalkoxy with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent, and C7-C20 alkaryl with or without a substituent; and R.sub.3, R.sub.12, Y, M and X are as defined for the Formula I, and the diimine-metal complexes represented by a formula III: ##STR00038## wherein, R.sub.5-R.sub.10 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C20 alkyl with or without a substituent, C2-C20 alkenyl with or without a substituent, C2-C20 alkynyl with or without a substituent, C3-C20 cycloalkyl with or without a substituent, C1-C20 alkoxy with or without a substituent, C2-C20 alkenoxy with or without a substituent, C2-C20 alkynoxy with or without a substituent, C3-C20 cycloalkoxy with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent, and C7-C20 alkaryl with or without a substituent; and R.sub.1, R.sub.2, M, X, Y and R.sub.11 are as defined for the Formula I.

    4. The method as claimed in claim 3, wherein in the formula III or III, R.sup.1-R.sup.11 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C10 alkyl with or without a substituent, C2-C10 alkenyl with or without a substituent, C2-C10 alkynyl with or without a substituent, C3-C10 cycloalkyl with or without a substituent, C1-C10 alkoxy with or without a substituent, C2-C10 alkenoxy with or without a substituent, C2-C10 alkynoxy with or without a substituent, C3-C10 cycloalkoxy with or without a substituent, C6-C15 aryl with or without a substituent, C7-C15 aralkyl with or without a substituent, and C7-C15 alkaryl with or without a substituent; preferably, R.sup.1-R.sup.11 are each independently selected from the group consisting of hydrogen, C1-C10 alkyl, halogenated C1-C10 alkyl, C1-C10 alkoxy, halogenated C1-C10 alkoxy and halogen, and more preferably from the group consisting of hydrogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkoxy and halogen, and in the formula III, R.sub.5-R.sub.10 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C10 alkyl with or without a substituent, C2-C10 alkenyl with or without a substituent, C2-C10 alkynyl with or without a substituent, C3-C10 cycloalkyl with or without a substituent, C1-C10 alkoxy with or without a substituent, C2-C10 alkenoxy with or without a substituent, C2-C10 alkynoxy with or without a substituent, C3-C10 cycloalkoxy with or without a substituent, C6-C15 aryl with or without a substituent, C7-C15 aralkyl with or without a substituent, and C7-C15 alkaryl with or without a substituent; preferably, R.sub.5-R.sub.10 are each independently selected from the group consisting of hydrogen, C1-C10 alkyl, halogenated C1-C10 alkyl, C1-C10 alkoxy, halogenated C1-C10 alkoxy, and halogen; and more preferably from the group consisting of hydrogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkoxy, and halogen.

    5. The method as claimed in claim 1, wherein the main catalyst comprises at least one diimine-metal complex represented by a formula III: ##STR00039## wherein, R.sup.1-R.sup.5 are independently selected from the group consisting of hydrogen, halogen, C1-C6 alkyl with or without a substituent and C1-C6 alkoxy with or without a substituent; R.sub.5-R.sub.10 are independently selected from the group consisting of hydrogen, halogen, C1-C6 alkyl and C1-C6 alkoxy; each M is nickel; each Y is O; each X is independently a halogen; and each R.sub.11 is independently a C1-C6 alkyl with or without a substituent.

    6. The method as claimed in claim 1, wherein the substituent is selected from the group consisting of halogen, hydroxy, C1-C10 alkyl, halogenated C1-C10 alkyl, C1-C10 alkoxy and halogenated C1-C10 alkoxy, and preferably from the group consisting of halogen, hydroxy, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy and halogenated C1-C6 alkoxy; preferably, the C1-C6 alkyl is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl and 3,3-dimethylbutyl; preferably, the C1-C6 alkoxy is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, n-pentoxy, isopentoxy, n-hexoxy, isohexoxy and 3,3-dimethylbutoxy; preferably, the halogen is selected from the group consisting of fluorine, chlorine, bromine and iodine.

    7. The method as claimed in claim 3, wherein the main catalyst comprises at least one complex selected from the group consisting of: the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=ethyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sub.3=isopropyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1-R.sup.3=methyl, R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=ethyl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sub.3=isopropyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1-R.sup.3=methyl, R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=ethyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sub.3=isopropyl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1-R.sup.3=methyl, R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the diimine-metal complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=methyl, R.sup.11=bromomethyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=i-Pr, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=Me, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=Me, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=ethyl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=isopropyl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=methyl, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=methyl, R.sub.3=isopropyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=isopropyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=isopropyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=isopropyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=methyl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=CH.sub.3, R.sup.11=bromomethyl, R.sub.3=isopropyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=Et, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=CH.sub.3, R.sup.11=CH.sub.2Br, R.sub.3=isopropyl, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sub.3=isopropyl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=CH.sub.3, R.sup.11=CH.sub.2Br, R.sup.3=ethyl, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=Me, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=CH.sub.3, R.sup.11=CH.sub.2Br, R.sub.12=ethyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=Br, R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=Me, R.sub.3=Et, R.sup.11=CH.sub.2Br, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=Me, R.sup.11=CH.sub.2Br, R.sub.3=isobutyl, R.sub.12=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=Me, R.sup.11=CH.sub.2Br, R.sub.3=isobutyl, R.sub.12=Et, M=Ni, Y=O, X=Br; and the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4-R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=Me, R.sup.11=CH.sub.2Br, R.sub.3=isobutyl, R.sub.12=Et, M=Ni, Y=O, X=Br.

    8. The method as claimed in claim 5, wherein the main catalyst comprises at least one complex selected from the group consisting of: the complex represented by the formula III, wherein R.sup.1=R.sup.3=isopropyl, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=Me, R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=Br, R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Me, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=isopropyl, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1R.sup.3=Me, R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=Br, R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=isopropyl, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=Me, R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=Br, R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4=R.sup.5=R.sub.5-R.sub.10=H, R.sub.11=isobutyl, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=isopropyl, R.sup.2=R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Et, R.sup.2=R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1-R.sup.3=Me, R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=Br, R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Br, R.sup.2=R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; the complex represented by the formula III, wherein R.sup.1=R.sup.3=Cl, R.sup.2=R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br; and the complex represented by the formula III, wherein R.sup.1=R.sup.3=F, R.sup.2=R.sup.4=R.sup.5=R.sub.5=R.sub.6=R.sub.9=R.sub.10=H, R.sub.7=R.sub.8=Me, R.sub.11=Et, M=Ni, Y=O, X=Br.

    9. The method as claimed in claim 1, wherein the main catalyst comprises at least one diimine-metal complex represented by a formula IV: ##STR00040## wherein, R.sub.1 and R.sub.2 are each independently a C1-C30 hydrocarbyl with or without a substituent; R.sub.21-R.sub.24 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C20 hydrocarbyl with or without a substituent and C1-C20 hydrocarbyloxy with or without a substituent, and two or more of R.sub.21-R.sub.24 groups are optionally joined to form a ring; each R.sub.12 is independently a C1-C20 hydrocarbyl with or without a substituent; each Y is independently a Group VIA non-metal atom; each M is independently a Group VIII metal; and each X is independently selected from the group consisting of halogen, C1-C10 hydrocarbyl with or without a substituent and C1-C10 hydrocarbyloxy with or without a substituent.

    10. The method as claimed in claim 9, having at least one of the following features: R.sub.1 and R.sub.2 are independently selected from the group consisting of C1-C20 alkyl with or without a substituent and C6-C20 aryl with or without a substituent, and preferably R.sub.1 and/or R.sub.2 are/is a group represented by formula A: ##STR00041## wherein, R.sup.1-R.sup.5 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C20 alkyl with or without a substituent, C2-C20 alkenyl with or without a substituent, C2-C20 alkynyl with or without a substituent, C3-C20 cycloalkyl with or without a substituent, C1-C20 alkoxy with or without a substituent, C2-C20 alkenoxy with or without a substituent, C2-C20 alkynoxy with or without a substituent, C3-C20 cycloalkoxy with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent, and C7-C20 alkaryl with or without a substituent, and two or more of R.sup.1-R.sup.5 groups are optionally joined to form a ring; preferably, wherein R.sup.1-R.sup.5 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C10 alkyl with or without a substituent, C2-C10 alkenyl with or without a substituent, C2-C10 alkynyl with or without a substituent, C3-C10 cycloalkyl with or without a substituent, C1-C10 alkoxy with or without a substituent, C2-C10 alkenoxy with or without a substituent, C2-C10 alkynoxy with or without a substituent, C3-C10 cycloalkoxy with or without a substituent, C6-C15 aryl with or without a substituent, C7-C15 aralkyl with or without a substituent, and C7-C15 alkaryl with or without a substituent; each M is independently selected from the group consisting of nickel and palladium; each Y is independently selected from the group consisting of O and S; each X is independently selected from the group consisting of halogen, C1-C10 alkyl with or without a substituent and C1-C10 alkoxy with or without a substituent, and preferably from the group consisting of halogen, C1-C6 alkyl with or without a substituent and C1-C6 alkoxy with or without a substituent; and each R.sub.12 is independently a C1-C20 alkyl with or without a substituent, preferably a C1-C10 alkyl with or without a substituent, and more preferably a C1-C6 alkyl with or without a substituent.

    11. The method as claimed in claim 9, wherein the main catalyst comprises at least one diimine-metal complex represented by a formula V: ##STR00042## wherein, R.sup.1-R.sup.10, R.sub.21-R.sub.24 are each independently selected from the group consisting of hydrogen, C1-C20 alkyl with or without a substituent, C2-C20 alkenyl with or without a substituent, C2-C20 alkynyl with or without a substituent, C3-C20 cycloalkyl with or without a substituent, C1-C20 alkoxy with or without a substituent, C2-C20 alkenoxy with or without a substituent, C2-C20 alkynoxy with or without a substituent, C3-C20 cycloalkoxy with or without a substituent, C6-C20 aryl with or without a substituent, C7-C20 aralkyl with or without a substituent, C7-C20 alkaryl with or without a substituent and halogen, two or more of R.sup.1-R.sup.10 are optionally joined to form a ring, and two or more of R.sub.21-R.sub.24 are optionally joined to form a ring; and R.sub.12, Y, M and X are as defined for the Formula I.

    12. The method as claimed in claim 11, wherein R.sup.1-R.sup.10, R.sub.21-R.sub.24 are each independently selected from the group consisting of hydrogen, halogen, hydroxy, C1-C10 alkyl with or without a substituent, C2-C10 alkenyl with or without a substituent, C2-C10 alkynyl with or without a substituent, C3-C10 cycloalkyl with or without a substituent, C1-C10 alkoxy with or without a substituent, C2-C10 alkenoxy with or without a substituent, C2-C10 alkynoxy with or without a substituent, C3-C10 cycloalkoxy with or without a substituent, C6-C15 aryl with or without a substituent, C7-C15 aralkyl with or without a substituent, and C7-C15 alkaryl with or without a substituent; preferably, R.sup.1-R.sup.10, R.sub.21-R.sub.24 are each independently selected from the group consisting of hydrogen, C1-C10 alkyl, halogenated C1-C10 alkyl, C1-C10 alkoxy, halogenated C1-C10 alkoxy, and halogen, and more preferably from the group consisting of hydrogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkoxy, and halogen.

    13. The method as claimed in claim 9, wherein the substituent is selected from the group consisting of halogen, hydroxy, C1-C10 alkyl, halogenated C1-C10 alkyl, C1-C10 alkoxy and halogenated C1-C10 alkoxy, and preferably from the group consisting of halogen, hydroxy, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy and halogenated C1-C6 alkoxy; preferably, the C1-C6 alkyl is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl and 3,3-dimethylbutyl; preferably, the C1-C6 alkoxy is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, n-pentoxy, isopentoxy, n-hexoxy, isohexoxy and 3,3-dimethylbutoxy; preferably, the halogen is selected from the group consisting of fluorine, chlorine, bromine and iodine.

    14. The method as claimed in claim 11, wherein the main catalyst comprises at least one complex selected from the group consisting of: 1) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 2) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 3) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 4) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 5) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 6) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 7) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 8) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 9) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 10) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 11) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 12) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 13) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 14) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.21=R.sub.22=R.sub.23=R.sub.24=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 15) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=H, R.sub.21=tert-butyl, R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 16) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=H, R.sub.21=tert-butyl, R.sub.23=R.sub.24=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 17) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=Et, M=Ni, Y=O, X=Br; 18) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=Et, M=Ni, Y=O, X=Br; 19) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=Et, M=Ni, Y=O, X=Br; 20) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=Et, M=Ni, Y=O, X=Br; 21) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=Et, M=Ni, Y=O, X=Br; 22) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 23) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 24) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 25) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 26) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 27) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 28) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.22=R.sub.23=R.sub.24=H, R.sub.21=tert-butyl, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; ##STR00043## 29) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 30) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 31) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 32) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 33) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 34) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 35) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=Et, M=Ni, Y=O, X=Br; 36) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 37) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 38) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 39) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 40) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 41) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 42) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=R.sub.31=R.sub.32=H, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 43) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 44) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 45) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 46) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 47) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 48) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 49) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 50) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=isopropyl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=R.sub.12=Et, M=Ni, Y=O, X=Br; 51) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Et, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 52) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Me, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 53) the complex represented by the formula V, wherein R.sup.1-R.sup.6=Me, R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 54) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Br, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; 55) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=Cl, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br; and 56) the complex represented by the formula V, wherein R.sup.1=R.sup.3=R.sup.4=R.sup.6=F, R.sup.2=R.sup.5=R.sup.7-R.sup.10=H, R.sub.31=R.sub.32=Et, R.sub.12=isobutyl, M=Ni, Y=O, X=Br.

    15. The method as claimed in claim 1, wherein: the olefin is at least one of olefins having 2-20 carbon atoms, or at least one of olefins having 2-16 carbon atoms, preferably the olefin is at least one of ethylene and alpha-olefins having 3-14 carbon atoms, or at least one of ethylene, alpha-olefins having 3-16 carbon atoms and C.sub.3-C.sub.16 cyclic olefins, and more preferably the olefin is at least one of ethylene and/or C.sub.2-C.sub.10 alpha-olefin, and/or, the unsaturated carboxylic ester is one or more of those represented by formula G: ##STR00044## wherein, L.sub.1-L.sub.3 are each independently H or a C1-C30 alkyl with or without a substituent; L.sub.4 is a C1-C30 alkylene group with a pendent group; and L.sub.5 is H or a C1-C30 alkyl with or without a substituent, or L.sub.5 is a C1-C20 alkyl or a C1-C20 alkyl haloalkyl, preferably, L.sub.1 and L.sub.2 are H; L.sub.3 is H or a C1-C20 alkyl, and more preferably H or a C1-C10 alkyl; L.sub.4 is a C1-C20 alkylene with a pendent group, and more preferably a C1-C0 alkylene with a pendent group; and L.sub.5 is a C1-C20 alkyl, preferably a C1-C10 alkyl, and more preferably a C1-C6 alkyl.

    16. The method as claimed in claim 15, having at least one of the following features: the substituent in the L.sub.1-L.sub.3 is one or more selected from the group consisting of halogen, C1-C10 alkyl, C1-C10 alkoxy, C6-C10 aryl, cyano and hydroxy, and more preferably one or more selected from the group consisting of C1-C6 alkyl, halogen and C1-C6 alkoxy; the pendent group in the L.sub.4 is one or more selected from the group consisting of halogen, C6-C20 aryl, C1-C20 alkyl and C1-C20 alkoxy, with the C6-C20 aryl, the C1-C20 alkyl and the C1-C20 alkoxy being optionally substituted by a substituent, which is preferably one or more selected from the group consisting of halogen, C1-C10 alkyl, C1-C10 alkoxy, C6-C10 aryl and hydroxy; the cocatalyst is selected from the group consisting of organoaluminum compounds and organoboron compounds; preferably, the organoaluminum compounds is one or more selected from the group consisting of alkylaluminoxanes, alkylaluminums and alkyl aluminum halides; preferably, the organoboron compound is selected from the group consisting of aromatic hydrocarbyl boron compounds and borates; a molar ratio of aluminum in the cocatalyst to M in the main catalyst is (10-10.sup.7):1, preferably (10-100,000):1, and more preferably (100-20,000):1; and/or a molar ratio of boron in the cocatalyst to M in the main catalyst is (0.1-1,000):1, preferably (0.1-500):1, and a molar ratio of the organoaluminum to M in the main catalyst is (10-10.sup.5):1; reaction temperature ranges from ?50? C. to 100? C., preferably from ?20? C. to 60? C., and more preferably from 0? C. to 50? C.; reaction time ranges from 10 to 200 min, and preferably from 20 to 60 min; and the reaction is carried out under anhydrous and oxygen-free conditions.

    17. The method as claimed in claim 15, having at least one of the following features: polymerization reaction is carried out in an alkane solvent, which is one or more of C3-C20 alkanes, preferably C3-C10 alkane; a concentration of the main catalyst in reaction system is from 0.00001 to 100 mmol/L, preferably from 0.0001 to 1 mmol/L, and more preferably from 0.001 to 0.5 mmol/L; a concentration of the unsaturated carboxylic ester monomer in reaction system is from 0.01 to 6,000 mmol/L, preferably from 0.1 to 1,000 mmol/L, and more preferably from 1 to 500 mmol/L.

    18. A polymer obtained by the preparation method as claimed in claim 1, wherein: the polymer as-polymerized is spherical and/or sphere-like, with an average particle size ranging from 0.05 to 50.0 mm, preferably from 0.5 to 20.0 mm, and more preferably from 1 to 10 mm or from 0.5 to 5 mm; and the polymer as-polymerized has a hollow structure, with a density of the polymer ranging from 0.2000 to 0.8500 g/cm.sup.3, and preferably from 0.3000 to 0.7500 g/cm.sup.3.

    19. (canceled)

    20. The copolymer of an olefin and an unsaturated carboxylic ester as claimed in claim 18, having at least one of the following features: the polymer has a weight average molecular weight of from 5,000 to 1,000,000, or from 5,000 to 800,000, or from 8,000-600,000, or from 10,000 to 600,000; the polymer has a molecular weight distribution of no more than 4.0, and preferably from 1.0 to 4.0; and in the polymer, a content of structural units derived from the unsaturated carboxylic ester represented by the formula G is from 0.1 to 30.0 mol %, and preferably from 0.1 to 10.0 mol %, or from 0.1 to 5.0 mol %.

    Description

    DESCRIPTION OF DRAWINGS

    [0232] FIG. 1 is a photograph of the spherical and/or sphere-like polymer obtained in the inventive Example 9.

    [0233] FIG. 2 is an electron microscope photograph of the polymer obtained in Example 35.

    EXAMPLES

    [0234] The present invention will be described in detail below in conjunction with the drawings and examples. It is necessary to point out that the following examples are used only to further illustrate the present invention, and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments to the present invention made by those skilled in the art in light of the disclosures still fall within the protection scope of the present invention.

    [0235] The analytical characterization instruments used herein are as follows: [0236] 1. .sup.1H NMR nuclear magnetic resonance instrument: Bruker DMX 300 (300 MHz), used to determine the structure of the complex ligand at 25? C., with tetramethyl silicon (TMS) as the internal standard. [0237] 2. Comonomer content of the polymer (content of structural units derived from the unsaturated carboxylic ester represented by the formula G): measured through .sup.1H NMR and .sup.13C NMR spectra recorded on a 400 MHz Bruker Avance 400 nuclear magnetic resonance spectrometer, using a 10 mm PASEX 13 probe, with the polymer sample being dissolved in 1,2,4-trichlorobenzene at 120? C. [0238] 3. Molecular weight and molecular weight distribution PDI (PDI=Mw/Mn) of polymer: measured by PL-GPC220 chromatograph, with trichlorobenzene as solvent, at 150? C. (standard sample: PS; flow rate: 1.0 mL/min; Columns: 3?Plgel 10 um M1?ED-B 300?7.5 nm). [0239] 4. Activity measurement method: (polymer weight (g)?60)/nickel (mol)?reaction time (min). [0240] 5. Polymer density: measured according to GB/T 6343-2009.

    [0241] The structure of the complexes used in Examples 1-11 is represented by Formula III:

    ##STR00015##

    Example 1

    1) Preparation of Ligand L1:

    [0242] Under nitrogen atmosphere, 2,6-diethylaniline (2.0 ml, 12 mmol) was dissolved in 20 ml of toluene, and 12 ml of trimethylaluminum (1.0 mol/L, 12 mmol) was added dropwise at normal temperature. The reaction was refluxed for 2 hours, and the system was then cooled to room temperature. Camphorquinone (0.831 g, 5 mmol) was added thereto, and the system was refluxed for 6 h. The reaction product was neutralized with aqueous sodium hydroxide solution, extracted with dichloromethane, dried over anhydrous magnesium sulfate, and then subjected to a column chromatography with petroleum ether/ethyl acetate as an eluent to afford yellow ligand L.sub.1. Yield: 69.2%. .sup.1H-NMR (CDCl.sub.3): ? 6.94-6.92 (m, 6H, C.sub.ArCH.sub.3), 2.56-2.51 (m, 4H, C.sub.ArCH.sub.3), 2.36-2.31 (m, 4H, C.sub.ArCH.sub.3), 1.82-1.78 (m, 4H, CH.sub.2), 1.54 (m, 1H), 1.24-1.18 (m, 12H), 1.09 (s, 3H, CH.sub.3), 0.94 (m, 6H, CH.sub.3).

    2) Preparation of Complex Ni.sub.1 (Represented by Formula III, Wherein R.sup.1, R.sup.3 are Ethyl; R.sup.2, R.sup.4-R.sup.7, R.sup.10 are Hydrogen; R.sup.8, R.sup.9, R.sup.11 are Methyl; R.sup.12 is Ethyl; M is Nickel; Y is O; and X is Br):

    [0243] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.258 g (0.6 mmol) of ligand L.sub.1 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.1 as brownish-red powdery solids. Yield: 78.2%. Elemental analysis (calculated for C.sub.64H.sub.90Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 47.96; H, 5.66; N, 3.50; experimental value (%): C, 47.48; H, 6.00; N, 3.26.

    3) Polymerization:

    [0244] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 47 ?L (0.30 mmol) of methyl 3,3-dimethyl-4-pentenoate, 0.30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), and 25 ?L of MAO (1.53 mol/L solution in toluene) were charged into the polymerization system, and then 12.5 ?L of complex Ni.sub.1 (1.0 mmol/L solution) was added thereto. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.63 mol %.

    Example 2

    [0245] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 47 ?L (0.30 mmol) of methyl 3,3-dimethyl-4-pentenoate, 0.3 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and then 12.5 ?L of complex Ni.sub.1 (1.0 mmol/L solution in toluene) was added thereto. The reaction was stirred at 10? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1.

    Example 3

    [0246] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.10 mL (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 ?L of AliBu.sub.3 (0.61 mmol), 50 ?L of triisobutylaluminum (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and then 12.5 ?L of complex Ni.sub.1 (1.0 mmol/L solution in toluene) was added thereto. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.92 mol %.

    Example 4

    [0247] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.5 mL (3.50 mmol) of ethyl 2-methyl-3-butenoate, and 0.57 mL of diisopropyldichlorosilane were charged into the polymerization system, and the contents were stirred for 2 h. Next, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 25.0 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 37.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were added thereto, followed by the addition of 12.5 ?L of complex Ni.sub.1 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 2.06 mol %.

    Example 5

    1) Preparation of Ligand L2:

    [0248] Under nitrogen atmosphere, 2,4,6-trimethyl-aniline (1.7 ml, 12 mmol) was dissolved in 20 ml of toluene, and 12 ml of trimethylaluminum (1.0M, 12 mmol) was added dropwise at normal temperature. The reaction was refluxed for 2 hours, and the system was then cooled to room temperature. Camphorquinone (0.831 g, 5 mmol) was added thereto, and the system was refluxed for 6 h. The reaction product was neutralized with aqueous sodium hydroxide solution, extracted with dichloromethane, and dried, and then subjected to a column chromatography to afford yellow ligand L2. Yield: 62.5%. .sup.1HNMR (300 MHz, CDCl.sub.3), ? (ppm) [with an isomer ratio of 1.2:1]: major isomer: 6.72 (s, 4H, ArH), 2.26-2.13 (m, 12H, C.sub.ArCH.sub.3), 1.87 (s, 6H, C.sub.ArCH.sub.3), 1.79 (m, 4H, CH.sub.2), 1.42 (m, 1H), 1.26 (s, 3H, CH.sub.3), 1.07 (s, 6H, CH.sub.3); minor isomer: 6.67 (s, 4H, ArH), 2.09-2.01 (m, 12H, C.sub.ArCH.sub.3), 1.85 (s, 6H, C.sub.ArCH.sub.3), 1.79 (m, 4H, CH.sub.2), 1.40 (m, 1H), 1.26 (s, 3H, CH.sub.3), 0.94 (s, 6H, CH.sub.3). 2) Preparation of complex Ni.sub.2 (represented by Formula III, wherein R.sup.1-R.sup.3 are methyl; R.sup.4-R.sup.7, R.sup.10 are hydrogen; R.sup.1, R.sup.9 and R.sup.11 are methyl; R.sub.12 is ethyl; M is nickel; Y is O; and X is Br): A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.240 g (0.6 mmol) of ligand L2 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.2 as brownish-red powdery solids. Yield: 78.6%. Elemental analysis (calculated for C.sub.60H.sub.82Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 46.59; H, 5.34; N, 3.62; experimental value (%): C, 46.24; H, 5.67; N, 3.21.

    3) Polymerization:

    [0249] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.63 mmol) of methyl 3,3-dimethyl-4-pentenoate, 160 ?L of AliBu.sub.3 (0.63 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni.sub.2 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1.

    Example 6

    [0250] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.58 mmol) of isobutyl 2-methyl-3-butenoate, 146 ?L of AliBu.sub.3 (0.58 mmol), 50 ?L of AlEt.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged thereto, followed by the addition of 12.5 ?L of complex Ni.sub.2 (1.0 mmol/L solution in toluene). The reaction was vigorously stirred at 50? C. for 30 minutes, with ethylene pressure being maintained at 15 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.78 mol %.

    Example 7

    [0251] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.500 mL (3.16 mmol) of methyl 3,3-dimethyl-4-pentenoate, and 0.57 mL of diisopropyldichlorosilane were charged thereto, and the contents were stirred for 2 h. Next, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 37.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were added thereto, followed by the addition of 6.2 ?L of complex Ni.sub.2 (1.0 mmol/L solution in toluene). The reaction was vigorously stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 10 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 2.16 mol %.

    Example 8

    [0252] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 L of AliBu.sub.3 (0.61 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 6.2 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 6.2 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni.sub.2 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1.

    Example 9

    [0253] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 100 ?L (0.58 mmol) of methyl 2-isopropyl-4-pentenoate, 15.6 mL of AliBu.sub.3 (61.4 mmol), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 mol) of tris(pentafluorophenyl)borane, and 11.5 mg (12.5 ?mol) of triphenylcarbonium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, followed by the addition of 1.9 mg (1.25 ?mol) of complex Ni.sub.2. The reaction was stirred at 20? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.96 mol %. The obtained polymer was in the form of granules, the particle size was 3.82 mm, the polymer had a hollow structure, and the density of the obtained polymer was 0.4182 g/cm.sup.3.

    Example 10

    [0254] 1) Preparation of ligand L3:

    [0255] Under nitrogen atmosphere, 2,6-dimethyl-4-bromo-aniline (2.45 g, 12 mmol) was dissolved in 20 ml of toluene, and 12 ml of trimethylaluminum (1.0M, 12 mmol) was added dropwise at normal temperature. The reaction was refluxed for 2 hours, and the system was then cooled to room temperature. Camphorquinone (0.831 g, 5 mmol) was added thereto, and the system was refluxed for 6 h. The reaction product was neutralized with aqueous sodium hydroxide solution, extracted with dichloromethane, and dried, and then subjected to a column chromatography to afford yellow ligand L3. Yield: 60.7%. .sup.1HNMR (300 MHz, CDCl.sub.3), ? (ppm) [with an isomer ratio of 1.1:1]: major isomer: 7.05 (s, 4H, ArH), 2.18 (m, 12H, C.sub.ArCH.sub.3), 1.85 (m, 4H, CH.sub.2), 1.37 (m, 1H), 1.26 (s, 3H, CH.sub.3), 1.06 (s, 6H, CH.sub.3); minor isomer: 7.02 (s, 4H, ArH), 2.04 (m, 12H, C.sub.ArCH.sub.3), 1.85 (m, 4H, CH.sub.2), 1.37 (m, 1H), 1.26 (s, 3H, CH.sub.3), 0.96 (s, 6H, CH.sub.3).

    2) Preparation of Complex Ni.sub.3 (Represented by Formula III, Wherein R.sup.1, R.sup.3 are Methyl; R.sup.2 is Br; R.sup.4-R.sup.7, R.sup.10 are Hydrogen; R.sup.8, R.sup.9 and R.sup.11 are Methyl; R.sub.12 is Ethyl; M is Nickel, Y is O, and X is Br):

    [0256] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.318 g (0.6 mmol) of ligand L.sub.3 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.3 as brownish-red powdery solids. Yield: 74.1%. Elemental analysis (calculated for C.sub.56H.sub.70Br.sub.10N.sub.4Ni.sub.3O.sub.2): C, 37.24; H, 3.91; N, 3.10; experimental value (%): C, 37.38; H, 4.30; N, 3.03.

    3) Polymerization:

    [0257] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 L of AliBu.sub.3 (0.61 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni.sub.3 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1.

    Example 11

    1) Preparation of Ligand L4:

    [0258] Under nitrogen atmosphere, 2,6-diisopropyl-aniline (2.30 ml, 12 mmol) was dissolved in 20 ml of toluene, and 12 ml of trimethylaluminum (1.0M, 12 mmol) was added dropwise at normal temperature. The reaction was refluxed for 2 hours, and the system was then cooled to room temperature. Dione B

    ##STR00016##

    (1.225 g, 5 mmol) was added thereto, and the system was refluxed for 6 h. The reaction product was neutralized with aqueous sodium hydroxide solution, extracted with dichloromethane, and dried, and then subjected to a column chromatography to afford yellow ligand L.sub.4. Yield: 62.7%. .sup.1H NMR (300 MHz, CDCl.sub.3), ? (ppm): 7.05-6.83 (m, 6H, ArH), 3.30 (m, 2H, CH.sub.2), 2.80 (m, 4H, CH(CH.sub.3).sub.2), 1.55 (m, 1H), 1.83 (m, 4H, CH.sub.2), 1.26 (d, 24H, CH(CH.sub.3).sub.2), 0.99 (s, 6H, CH.sub.3).
    2) Preparation of Complex Ni.sub.4 (Represented by the Structural Formula III, Wherein R.sup.1, R.sup.3 are Isopropyl; R.sup.2, R.sup.4-R.sup.7, R.sup.10 are Hydrogen; R.sup.1, R.sup.9 are Methyl; R.sup.11 is CH.sub.2Br; R.sub.12 is Ethyl; M is Nickel, Y is O, and X is Br):

    [0259] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.338 g (0.6 mmol) of ligand L.sub.4 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.4 as brownish-red powdery solids. Yield: 80.2%. Elemental analysis (calculated for C.sub.72H.sub.104Br.sub.8N.sub.4Ni.sub.3O.sub.2): C, 46.17; H, 5.60; N, 2.99; experimental value (%): C, 46.24; H, 5.80; N, 3.13.

    3) Polymerization:

    [0260] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.58 mmol) of isobutyl 2-methyl-3-butenoate, 146 L of AliBu.sub.3 (95%), 50 ?L of AlEt.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged thereto, followed by the addition of 12.5 ?L of complex Ni.sub.4 (1.0 mmol/L solution in toluene). The reaction was vigorously stirred at 10? C. for 10 minutes, with ethylene pressure being maintained at 10 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.16 mol %.

    Comparative Example 1

    [0261] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.71 mmol) of methyl 5-hexenoate, 114 ?L of AliBu.sub.3 (95%), 50 ?L of AlEt.sub.3 (0.01 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni.sub.2 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1.

    Comparative Example 2

    [0262] This comparative example was carried out as described in Comparative Example 1, except that the catalyst used was different. In this comparative example, 0.025 ?mol of comparative catalyst H was used.

    ##STR00017##

    TABLE-US-00001 TABLE 1 Is there a spherical or Polymerization sphere-like polymer Activity 10.sup.6 g .Math. Mw in the copolymer?/ No. Complex mol.sup.?1(Ni) .Math. h.sup.?1 (?10.sup.4) PDI Particle size (mm) Example 1 Ni.sub.1 6.82 10.87 3.24 Yes/0.90 Example 2 Ni.sub.1 4.39 32.94 2.58 Yes/0.97 Example 3 Ni.sub.1 7.24 10.32 2.54 Yes/0.93 Example 4 Ni.sub.1 4.46 13.47 2.55 Yes/1.22 Example 5 Ni.sub.2 7.61 9.23 3.42 Yes/1.20 Example 6 Ni.sub.2 8.92 14.22 3.27 Yes/1.43 Example 7 Ni.sub.2 6.82 12.94 3.43 Yes/1.54 Example 8 Ni.sub.2 7.91 10.32 2.97 Yes/1.07 Example 9 Ni.sub.2 10.80 18.36 3.43 Yes/3.82 Example 10 Ni.sub.3 6.42 7.32 4.13 Yes/1.21 Example 11 Ni.sub.4 8.37 58.24 3.86 Yes/1.82 Comp. Ex. 1 Ni.sub.2 2.94 10.28 3.42 No Comp. Ex. 2 H 2.29 9.37 3.63 No

    [0263] It can be seen from Table 1 that when the catalysts of the invention catalyze the copolymerization of ethylene with an unsaturated carboxylic ester, they exhibit higher polymerization activities. The copolymerization activities of the catalysts of the invention can be up to 10.8?10.sup.6 g.Math.mol.sup.?1(Ni).Math.h.sup.?1.

    [0264] The comonomer content of the polymer obtained in Example 7 can be up to 2.1%. In addition, by adjusting polymerization conditions, copolymer products with good particle morphology can be obtained without subsequent processing steps such as granulation, and the resultant polymer products are not prone to fouling in the reactor and are convenient for transportation.

    [0265] The ligands and complexes used in examples 12-20 are represented by formula K and formula VI, respectively:

    ##STR00018##

    Example 12

    [0266] ##STR00019##

    [0267] Ligand L5 (represented by the structural Formula K, wherein R.sup.1, R.sup.3, R.sup.4, and R.sup.6 are methyl, R.sup.2, R.sup.8, R.sup.7-R.sup.10, R.sub.21, and R.sub.22 are hydrogen) was prepared by following the literature Organometallics, 2013, 32, 2291-2299.

    Preparation of Complex Ni.sub.5 (Represented by the Structural Formula VI, Wherein R.sup.1, R.sup.3, R.sup.4, and R.sup.6 are Methyl, R.sup.2, R.sup.8, R.sup.7-R.sup.10, R.sub.21 and R.sub.22 are Hydrogen, R.sub.12 is Ethyl, M is Nickel, Y is O, and X is Br):

    [0268] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.264 g (0.6 mmol) of ligand L.sub.5 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.5 as brownish-red powdery solids. Yield: 78.2%. Elemental analysis (calculated for C.sub.68H.sub.66Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 50.21; H, 4.09; N, 3.44; experimental value (%): C, 50.38; H, 4.22; N, 3.76.

    3) Polymerization:

    [0269] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.30 mmol (47 ?L) of methyl 3,3-dimethyl-4-pentenoate, 0.30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), and 25 ?L of MAO (1.53 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni.sub.5 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2.

    Example 13

    [0270] Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.30 mmol (47 ?L) of methyl 3,3-dimethyl-4-pentenoate, 0.30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni.sub.5 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2, and the comonomer content of the obtained polymer was 0.84 mol %. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.84 mol %.

    Example 14

    [0271] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 L (0.61 mmol) of AliBu.sub.3, 50 ?L of triisobutylaluminum (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni.sub.5 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2.

    Example 15

    [0272] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.50 mL (3.16 mmol) of methyl 3,3-dimethyl-4-pentenoate, and 0.57 mL diisopropyldichlorosilane were charged into the polymerization system, and the contents were stirred for 2 hrs. Then, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were added thereto, and 12.5 ?L of complex Ni.sub.5 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 14 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2, and the comonomer content of the obtained polymer was 1.25 mol %. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 1.45 mol %.

    Example 16

    [0273] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 L (0.61 mmol) of AliBu.sub.3, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni.sub.5 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 50? C. for 10 minutes, with ethylene pressure being maintained at 20 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2.

    Example 17

    [0274] ##STR00020##

    Preparation of ligand L6 (represented by the structural formula K, wherein R.sup.1, R.sup.3, R.sup.4, R.sup.6 are methyl; R.sup.2, R.sup.5 are bromine; R.sup.7-R.sup.10, R.sub.22 are hydrogen; and R.sub.21 is tert-butyl): Compound J (1.77 g, 5.1 mmol) and 2,6-dimethyl-4-bromo-aniline (2.3 g, 11.3 mmol) were refluxed, in the presence of p-toluenesulfonic acid as a catalyst, in 100 mL of toluene for 1 day. The solvent was removed after filtration, and the residue was dissolved in dichloromethane and separated by column chromatography with petroleum ether/ethyl acetate as an eluant, to afford yellow solids L6. Yield: 78%. .sup.1H NMR (CDCl.sub.3, ? ppm): 1.84 (s, 12H), 1.19 (s, 18H), 4.70 (s, 2H), 7.04 (8H), 7.12 (s, 2H).
    Preparation of Complex Ni.sub.6 (Represented by the Structural Formula VI, Wherein R.sup.1, R.sup.3, R.sup.4, R.sup.6 are Methyl; R.sup.2, R.sup.5 are Bromine; R.sup.7-R.sup.10, R.sub.22 are Hydrogen; R.sub.21 is Tert-Butyl; R.sub.12 is Ethyl; M is Nickel, Y is O, and X is Br):

    [0275] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.426 g (0.6 mmol) of ligand L.sub.6 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.6 as brownish-red powdery solids. Yield: 82.0%. Elemental analysis (calculated for C.sub.84H.sub.94Br.sub.10N.sub.4Ni.sub.3O.sub.2): C, 46.56; H, 4.37; N, 2.59; experimental value (%): C, 46.43; H, 4.72; N, 2.98.

    [0276] Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.58 mmol) of isobutyl 2-methyl-3-butenoate, 146 ?L (0.58 mmol) of AliBu.sub.3 (95%), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni.sub.6 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2.

    Example 18

    [0277] ##STR00021##

    1) Ligand L7 was prepared by following Patent CN106397264.
    2) Preparation of complex Ni.sub.7 (represented by the structural formula VI, wherein R.sup.1, R.sup.3, R.sup.4 and R.sup.6 are ethyl, R.sup.2, R.sup.5, R.sup.7-R.sup.10 and R.sub.22 are hydrogen, R.sub.21 is tert-butyl, R.sub.12 is ethyl, M is nickel, Y is O, and X is Br):

    [0278] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.365 g (0.6 mmol) of ligand L.sub.7 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.7 as brownish-red powdery solids. Yield: 82.0%. Elemental analysis (calculated for C.sub.92H.sub.114Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 56.28; H, 5.85; N, 2.85; experimental value (%): C, 56.43; H, 6.12; N, 3.08.

    [0279] 3) Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.58 mmol) of methyl 2-isopropyl-4-pentenoate, 146 ?L (0.58 mmol) of AliBu.sub.3, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni.sub.7 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 2.

    Example 19

    [0280] ##STR00022##

    1) Ligand L8 was prepared by following patent application CN201510462932.2.
    2) Preparation of complex Ni.sub.8: A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.341 g (0.6 mmol) of ligand L8 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni.sub.8 as brownish-red powdery solids. Yield: 82.1%. Elemental analysis (calculated for C.sub.88H.sub.82Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 56.13; H, 4.39; N, 2.98; experimental value (%): C, 56.28; H, 4.62; N, 3.24.

    [0281] 3) Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.58 mmol) of isobutyl 2-methyl-3-butenoate, 146 ?L (0.58 mmol) of AliBu.sub.3, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged thereto, followed by the addition of 12.5 ?L of complex Ni.sub.8 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 2.

    Example 20

    [0282] Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (57.5 mmol) of isobutyl 2-methyl-3-butenoate, 14.6 mL of AliBu.sub.3 (95%), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 12.8 mg (25.0 ?mol) of tris(pentafluorophenyl)borane, and 34.5 mg (37.5 ?mol) of triphenylcarbonium tetrakis(pentafluorophenyl)borate were charged thereto, followed by the addition of 2.4 mg (1.25 ?mol) of complex Ni.sub.8. The reaction was vigorously stirred at 20? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 2. The density of the obtained polymer was 0.6842 g/cm.sup.3.

    Comparative Example 3

    [0283] 10 atm Ethylene Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.71 mmol) of methyl 5-hexenoate, 114 ?L (0.44 mmol) of AliBu.sub.3, and 25 ?L of MAO (1.53 mol/L solution in toluene) were charged thereto, and 37.5 ?L of comparative catalyst T (having a structure shown below) (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was vigorously stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 14 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 2. The comonomer content of the resulting polymer was 0.53 mol %.

    ##STR00023##

    TABLE-US-00002 TABLE 2 Is there a spherical or Polymerization sphere-like polymer Activity 10.sup.6 g .Math. Mw in the copolymer?/ No. Complex mol.sup.?1(Ni) .Math. h.sup.?1 (?10.sup.4) PDI Particle size (mm) Example 12 Ni.sub.5 1.54 6.42 4.37 Yes/1.12 Example 13 Ni.sub.5 2.04 5.32 3.54 Yes/1.13 Example 14 Ni.sub.5 1.27 3.21 3.44 Yes/1.10 Example 15 Ni.sub.5 0.94 1.76 3.13 Yes/1.89 Example 16 Ni.sub.5 4.27 10.22 3.44 Yes/1.54 Example 17 Ni.sub.6 2.57 7.62 3.28 Yes/1.14 Example 18 Ni.sub.7 4.24 21.47 3.62 Yes/1.82 Example 19 Ni.sub.8 4.36 7.33 3.45 Yes/1.52 Example 20 Ni.sub.8 6.42 23.27 3.25 Yes/3.32 Comp. Ex. 3 T 0.77 3.24 3.20 No

    [0284] It can be seen from Table 2 that, compared to the comparative example, the catalysts of the invention exhibit higher polymerization activities when catalyzing the copolymerization of ethylene with an unsaturated carboxylic ester. The copolymerization activities of the catalysts of the invention can be up to 6.42?10.sup.6 g.Math.mol.sup.?1(Ni).Math.h.sup.?1. In addition, by adjusting polymerization conditions, copolymer products with good particle morphology can be obtained without subsequent processing steps such as granulation, and the resultant polymer products are not prone to fouling in the reactor and are convenient for transportation.

    [0285] The following ligands and complexes are involved in the description of the following examples 21-31:

    ##STR00024## [0286] A2 is the ?-diimine compound represented by Formula VII, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3; [0287] ligand L9 is the aminoimine compound represented by Formula VIII, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3; [0288] ligand L10 is the aminoimine compound represented by Formula VIII, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3; R.sub.3=CH.sub.3; [0289] ligand L11 is the aminoimine compound represented by Formula VIII, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3; R.sup.3=Et; [0290] complex Ni9 is the complex represented by Formula III, wherein R.sup.1=R.sup.3=Me, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; [0291] complex Ni10 is the complex represented by Formula III, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=CH.sub.3, R.sub.12=Et, M=Ni, Y=O, X=Br; [0292] complex Ni11 is the complex represented by Formula III, wherein R.sup.1=R.sup.3=iPr, R.sup.2=R.sup.4=R.sup.5=R.sup.6=R.sup.7=R.sup.10=H, R.sup.8=R.sup.9=R.sup.11=CH.sub.3, R.sub.3=Et, R.sub.12=Et, M=Ni, Y=O, X=Br.

    Example 21

    [0293] 1) Preparation of ligand L9:

    [0294] 1.5 ml (12 mmol) of 2,6-dimethylaniline was reacted with 57 ml of 1M trimethylaluminum in toluene with refluxing for 3 h. Next, camphorquinone (1.05 g, 5 mmol) was added thereto, and the reflux reaction was continued for 8 hours. After cooling, sodium hydroxide/ice water was used to terminate the reaction. The reaction mixture was extracted with ethyl acetate, and the organic phases were combined, dried over anhydrous magnesium sulfate, and separated through a column chromatography with petroleum ether/ethyl acetate as an eluent to afford the ligand L9 as colorless crystals. Yield: 70.2%. .sup.1HNMR ? (ppm) 7.00-6.89 (m, 6H, ArH), 3.57 (s, 1H, NH), 2.18 (s, 6H, C.sub.ArCH.sub.3), 2.05 (s, 6H, CH.sub.3), 1.74 (m, 4H, CH.sub.2), 1.44 (s, 3H, CH.sub.3), 1.35 (m, 1H), 1.21 (s, 3H, CH.sub.3), 1.01 (s, 3H, CH.sub.3), 0.87 (s, 3H, CH.sub.3).

    [0295] 2) Preparation of complex Ni9: A solution of (DME)NiBr.sub.2 (277 mg, 0.9 mmol) in ethanol (10 mL) was added dropwise to a solution of ligand L9 (233 mg, 0.6 mmol) in dichloromethane (10 mL). The reaction was stirred at room temperature for 6 h to give precipitates. A filtration was performed, and the filter cake was washed with diethyl ether and dried to afford yellow powdery solids. Yield: 70%. Elemental analysis (calculated for C.sub.58H.sub.82Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 45.75; H, 5.43; N, 3.68; experimental value (%): C, 45.56; H, 5.83; N, 3.46.

    [0296] 3) After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 30 mmol (4.7 mL) of methyl 3,3-dimethyl-4-pentenoate, 30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), and 2.5 mL of MAO (1.53 mol/L solution in toluene) were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni.sub.9 was added simultaneously. The reaction was stirred at 10? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 22

    [0297] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 30 mmol (4.7 mL) of methyl 3,3-dimethyl-4-pentenoate, 30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 30? C. for 10 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 23

    [0298] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 30 mmol (4.7 mL) of methyl 3,3-dimethyl-4-pentenoate, 30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 30? C. for 20 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 24

    [0299] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 30 mmol (4.7 mL) of methyl 3,3-dimethyl-4-pentenoate, 30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3. The density of the obtained polymer was 0.5725 g/cm.sup.3. The prepared copolymer was in the form of particles, which were of spherical shape having a particle size of about 2 mm.

    Example 25

    [0300] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 30 mmol (4.7 mL) of methyl 3,3-dimethyl-4-pentenoate, 30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni.sub.9 was added simultaneously. The reaction was stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3. The density of the obtained polymer was 0.3742 g/cm.sup.3.

    Example 26

    [0301] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (61.4 mmol) of ethyl 2-methyl-4-pentenoate, 15.6 mL (61.4 mmol) of AliBu.sub.3 (95%), 0.5 mL of triisobutylaluminum (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 40? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 27

    [0302] After having been continuously dried at 130? C. for 6 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 400 mL of hexane, 50 mL (316 mmol) of methyl 3,3-dimethyl-4-pentenoate, and 57.2 mL of diisopropyldichlorosilane were charged into the polymerization system, and the contents were stirred for 2 hours. Next, 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged thereto, and 1.9 mg (1.25 ?mol) of complex Ni.sub.9 was added simultaneously. The reaction was stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 28

    [0303] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (61.4 mmol) of ethyl 2-methyl-4-pentenoate, 31.2 mL (122.8 mmol) of AliBu.sub.3 (95%), 0.5 mL of triisobutylaluminum (1.0 mol/L solution in heptane), 6.4 mg (12.5 mol) of tris(pentafluorophenyl)borane, and 30.0 mg (37.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 29

    [0304] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (57.5 mmol) of isobutyl 2-methyl-3-butenoate, 14.6 mL (57.5 mmol) of AliBu.sub.3 (95%), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 11.5 mg (12.5 ?mol) of triphenylcarbonium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Example 30

    1) Preparation of Ligand L10:

    [0305] To 3.88 g (8 mmol) of ?-diimine Compound A2 were successively charged with 30 ml of toluene and 16 ml of 1M trimethylaluminum (16 mmol), and the contents were allowed to react with refluxing for 8 hours. Sodium hydroxide/ice water was used to terminate the reaction. The reaction mixture was extracted with ethyl acetate, and the organic phases were combined, dried over anhydrous magnesium sulfate, and separated through a column chromatography with petroleum ether/ethyl acetate as an eluent to afford ligand L10 as colorless crystals. Yield: 84.2%. .sup.1HNMR ? (ppm) 7.19-7.06 (m, 6H, ArH), 3.42 (s, 1H, NH), 2.98 (m, 2H, CH(CH.sub.3).sub.2), 2.88 (m, 2H, CH(CH.sub.3).sub.2), 2.32 (m, 1H), 1.81 (m, 4H, CH.sub.2), 1.50 (s, 3H, CH.sub.3), 1.21 (m, 24H, CH.sub.3), 0.92 (s, 3H, CH.sub.3), 0.75 (s, 3H, CH.sub.3), 0.72 (s, 3H, CH.sub.3).

    [0306] 2) Preparation of complex Ni10: A solution of (DME)NiBr.sub.2 (277 mg, 0.9 mmol) in ethanol (10 mL) was added dropwise to a solution of ligand L10 (300 mg, 0.6 mmol) in dichloromethane (10 mL). The reaction was stirred at room temperature for 6 h to give precipitates. A filtration was performed, and the filter cake was washed with diethyl ether and dried to afford red powdery solids. Yield: 78%. Elemental analysis (calculated for C.sub.74H.sub.114Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 50.87; H, 6.58; N, 3.21; experimental value (%): C, 50.57; H, 6.73; N, 3.04.

    [0307] 3) After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (57.5 mmol) of isobutyl 2-methyl-3-butenoate, 14.6 mL (57.5 mmol) of AliBu.sub.3 (95%), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 11.5 mg (12.5 ?mol) of triphenylcarbonium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 2.2 mg (1.25 ?mol) of complex Ni10 was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3. The density of the obtained polymer was 0.6904 g/cm.sup.3.

    Example 31

    Preparation of Ligand L11:

    [0308] To 3.88 g (8 mmol) of ?-diimine Compound A2 were successively charged with 30 ml of diethyl ether and 4 ml of 2M diethylzinc (8 mmol), and the contents were stirred at a normal temperature for 3 hours. Ice water was used to terminate the reaction. The reaction mixture was extracted with ethyl acetate, and the organic phases were combined, dried over anhydrous magnesium sulfate, and separated through a column chromatography with petroleum ether/ethyl acetate as an eluent to afford ligand L11 as colorless crystals. Yield: 52.1%. .sup.1HNMR ? (ppm) 7.17-7.06 (m, 6H, ArH), 4.44 (s, 1H, NH), 2.98 (m, 2H, CH(CH.sub.3).sub.2), 2.87 (m, 2H, CH(CH.sub.3).sub.2), 2.33 (m, 1H), 1.86 (m, 2H, CH.sub.2), 1.81 (m, 4H, CH.sub.2), 1.21 (m, 24H, CH.sub.3), 1.08 (t, 3H, CH.sub.3), 0.93 (s, 3H, CH.sub.3), 0.75 (s, 3H, CH.sub.3), 0.72 (s, 3H, CH.sub.3).

    [0309] 2) Preparation of complex Ni11: A solution of (DME)NiBr.sub.2 (277 mg, 0.9 mmol) in ethanol (10 mL) was added dropwise to a solution of ligand L11 (309 mg, 0.6 mmol) in dichloromethane (10 mL). The reaction was stirred at room temperature for 6 h to give precipitates. A filtration was performed, and the filter cake was washed with diethyl ether and dried to afford red powdery solids. Yield: 72%. Elemental analysis (calculated for C.sub.76H.sub.118Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 51.42; H, 6.70; N, 3.16; experimental value (%): C, 51.29; H, 6.98; N, 3.04.

    [0310] 3) After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (61.4 mmol) of ethyl 2-methyl-4-pentenoate, 15.6 mL (61.4 mmol) of AliBu.sub.3 (95%), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 2.2 mg (1.25 ?mol) of complex Ni11 was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    Comparative Example 4

    [0311] After having been continuously dried at 130? C. for 6 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (71 mmol) of methyl 5-hexenoate, 11.4 mL of AliBu.sub.3 (95%), 0.50 mL of AlEt.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 1.9 mg (1.25 ?mol) of complex Ni9 was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 3.

    TABLE-US-00003 TABLE 3 Content of Is there a structural units spherical derived from the or sphere- Polymerization unsaturated like polymer in Activity carboxylic ester the copolymer?/ 10.sup.6 g .Math. mol.sup.?1 Mw represented by Particle size No. Complex (Ni) .Math. h.sup.?1 (?10.sup.4) PDI formula G, mol % (mm) Example 21 Ni9 1.36 29.20 2.32 0.42 Yes/2.2 Example 22 Ni9 4.67 5.78 2.12 0.43 Yes/1.1 Example 23 Ni9 3.54 7.04 2.13 0.42 Yes/1.7 Example 24 Ni9 2.73 8.62 2.14 0.43 Yes/2.0 Example 25 Ni9 2.12 9.36 2.16 0.41 Yes/5.0 Example 26 Ni9 2.42 6.41 2.23 0.56 Yes/1.8 Example 27 Ni9 1.83 9.34 2.24 1.13 Yes/3.2 Example 28 Ni9 1.96 7.37 2.25 0.52 Yes/2.1 Example 29 Ni9 2.54 7.12 2.37 0.51 Yes/2.2 Example 30 Ni10 4.27 19.42 2.71 0.50 Yes/2.3 Example 31 Ni11 4.66 17.31 2.26 0.50 Yes/2.5 Comp. Ex. 4 Ni9 1.04 5.23 2.31 0.30 No

    [0312] It can be seen from Table 3 that when the catalysts of the invention catalyze the copolymerization of ethylene with an unsaturated carboxylic ester, they exhibit higher polymerization activities. The copolymerization activities of the catalysts of the invention can be up to 4.66?10.sup.6 g.Math.mol.sup.?1(Ni).Math.h.sup.?1. In addition, by adjusting polymerization conditions, copolymer products with good particle morphology can be obtained.

    [0313] Ligands L12-L16 involved in the following Examples 32can be synthesized by referring to literature: Organometallics 2011, 30, 5480-5486.

    Example 32

    [0314] Preparation of complex Ni12

    ##STR00025##

    [0315] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.249 g (0.6 mmol) of ligand L.sub.12 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni12 as brownish-red powdery solids. Yield: 84.3%. Elemental analysis (calculated for C.sub.64H.sub.66Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 48.69; H, 4.21; N, 3.55; experimental value (%): C, 48.54; H, 4.47; N, 3.21.

    [0316] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 47 ?L (0.30 mmol) of methyl 3,3-dimethyl-4-pentenoate, 0.30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 10 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 1. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.74 mol %.

    Example 33

    [0317] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 47 ?L (0.30 mmol) of methyl 3,3-dimethyl-4-pentenoate, 0.30 mL of AlEt.sub.3 (1.0 mol/L solution in hexane), and 25 ?L of MAO (1.53 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.75 mol %.

    Example 34

    [0318] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 ?L of AliBu.sub.3 (95%, 0.61 mmol), 50 ?L of triisobutylaluminum (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.93 mol %.

    Example 35

    [0319] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 L of AliBu.sub.3 (95%, 0.61 mmol), 50 ?L of triisobutylaluminum (0.1 mol/L solution in ?heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 37.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene). The reaction was stirred at 10? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.90 mol %. Electron micrograph of the polymer is shown in FIG. 2.

    Example 36

    [0320] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.50 mL (3.16 mmol) of methyl 3,3-dimethyl-4-pentenoate, and 0.57 mL of diisopropyldichlorosilane were charged into the polymerization system, and the contents were stirred for 2 hours. Next, 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 25.0 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), 37.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene), and 12.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene) were added thereto. The reaction was stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 1.72 mol %.

    Example 37

    [0321] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 ?L of AliBu.sub.3 (95%, 0.61 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 50? C. for 20 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.64 mol %.

    Example 38

    [0322] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10.0 mL (57.5 mmol) of isobutyl 2-methyl-3-butenoate, 14.6 mL of AliBu.sub.3 (95%, 57.5 mmol), 0.5 mL of AlMe.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 11.5 mg (12.5 ?mol) of triphenylcarbonium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, and 2.0 mg (1.25 ?mol) of complex Ni12 was added simultaneously. The reaction was stirred at 30? C. for 60 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.94 mol %. The density of the obtained polymer was 0.4014 g/cm.sup.3.

    Example 39

    [0323] Preparation of complex Ni2

    ##STR00026##

    [0324] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.267 g (0.6 mmol) of ligand L13 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni13 as brownish-red powdery solids. Yield: 74.0%. Elemental analysis (calculated for C.sub.68H.sub.74Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 49.96; H, 4.56; N, 3.43; experimental value (%): C, 49.54; H, 5.11; N, 3.20.

    [0325] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.61 mmol) of ethyl 2-methyl-4-pentenoate, 156 L of AliBu.sub.3 (95%, 0.61 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni13 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.70 mol %.

    Example 40

    Preparation of Complex Ni14

    [0326] ##STR00027##

    [0327] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in 2-methyl-1-propanol (10 mL) was added slowly dropwise to a solution of 0.267 g (0.6 mmol) of ligand L13 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni14 as brownish-red powdery solids. Yield: 74.0%. Elemental analysis (calculated for C.sub.72H.sub.82Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 51.14; H, 4.89; N, 3.31; experimental value (%): C, 51.22; H, 5.21; N, 3.20.

    [0328] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.58 mmol) of isobutyl 2-methyl-3-butenoate, 146 L of AliBu.sub.3 (95%, 0.58 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, and 12.5 ?L of complex Ni14 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.71 mol %.

    Example 41

    Preparation of Complex Ni15

    [0329] ##STR00028##

    [0330] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.389 g (0.6 mmol) of ligand L14 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni15 as brownish-red powdery solids. Yield: 74.1%. Elemental analysis (calculated for C.sub.52H.sub.34Br.sub.14N.sub.4Ni.sub.3O.sub.2): C, 30.59; H, 1.68; N, 2.74; experimental value (%): C, 30.72; H, 1.97; N, 2.48.

    [0331] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.10 mL (0.70 mmol) of ethyl 2-methyl-3-butenoate, 178 L of AliBu.sub.3 (95%, 0.70 mmol), 50 ?L of AlMe.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of triphenylcarbonium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged thereto, followed by the addition of 12.5 ?L of complex Ni15 (1.0 mmol/L solution in toluene). The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 1.03 mol %.

    Example 42

    [0332] ##STR00029##

    Preparation of Complex Ni16

    [0333] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.233 g (0.6 mmol) of ligand L15 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni16 as brownish-red powdery solids. Yield: 78.2%. Elemental analysis (calculated for C.sub.60H.sub.58Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 47.33; H, 3.84; N, 3.68; experimental value (%): C, 47.38; H, 4.00; N, 3.46.

    [0334] After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 mL of hexane, 10 mL (57.5 mmol) of methyl 2-isopropyl-4-pentenoate, 14.6 mL of AliBu.sub.3 (95%, 57.5 mmol), 0.50 mL of AlEt.sub.3 (1.0 mol/L solution in heptane), 6.4 mg (12.5 ?mol) of tris(pentafluorophenyl)borane, and 10.0 mg (12.5 ?mol) of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate were charged into the polymerization system, followed by the addition of 1.9 mg (1.25 ?mol) of complex Ni16. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.94 mol %. The density of the obtained polymer was 0.6921 g/cm.sup.3.

    Example 43

    [0335] ##STR00030##

    [0336] A solution of 0.277 g (0.9 mmol) of (DME)NiBr.sub.2 in ethanol (10 mL) was added slowly dropwise to a solution of 0.284 g (0.6 mmol) of ligand L16 in dichloromethane (10 mL). The color of the solution immediately changed to deep red, and a large quantity of precipitants was formed. The reaction was stirred at room temperature for 6 h, and then anhydrous diethyl ether was added to perform precipitation. A filtration was performed to afford a filter cake, and the filter cake was washed with anhydrous diethyl ether and dried in vacuum to afford Ni17 as brownish-red powdery solids. Yield: 75.2%. Elemental analysis (calculated for C.sub.72H.sub.82Br.sub.6N.sub.4Ni.sub.3O.sub.2): C, 51.14; H, 4.89; N, 3.31; experimental value (%): C, 50.82; H, 5.12; N, 3.07.

    [0337] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 0.61 mmol (100 ?L) of ethyl 2-methyl-4-pentenoate, 156 L of AliBu.sub.3 (95%, 0.61 mmol), 50 ?L of AlEt.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene), and 12.5 ?L of complex Ni17 (1.0 mmol/L solution in toluene) were charged thereto. The reaction was vigorously stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.96 mol %.

    Comparative Example 5

    [0338] After having been continuously dried at 130? C. for 2 hrs, a 7 mL stainless steel glass-lined polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 4.0 mL of heptane, 100 ?L (0.71 mmol) of methyl 5-hexenoate, 114 ?L of AliBu.sub.3 (95%, 0.44 mmol), 50 ?L of AlEt.sub.3 (0.1 mol/L solution in heptane), 12.5 ?L of tris(pentafluorophenyl)borane (0.01 mol/L solution in toluene), and 12.5 ?L of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (0.01 mol/L solution in toluene) were charged into the polymerization system, followed by the addition of 12.5 ?L of complex Ni12 (1.0 mmol/L solution in toluene) was added simultaneously. The reaction was stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. Finally, the reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The polymerization activity and the performance parameters of the polymer are shown in Table 4. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.76 mol %.

    Comparative Example 6

    [0339] 10 atm Ethylene Polymerization: After having been continuously dried at 130? C. for 2 hrs, a 1 L stainless steel polymerization autoclave equipped with mechanical stirring was vacuumed while hot and then filled with N.sub.2 gas 3 times. 450 ml of hexane, 10.0 mL (44.5 mmol) of methyl 10-undecenoate, 11.4 mL of AliBu.sub.3 (95%), and 2.8 mL of MAO (1.53 mol/L solution in toluene) were charged thereto, and 2.3 mg (3.75 ?mol) of comparative catalyst A (having a structure represented by Formula 1 below) was added simultaneously. The reaction was vigorously stirred at 30? C. for 30 minutes, with ethylene pressure being maintained at 10 atm. The reaction mixture was neutralized with an ethanol solution acidified with 10 wt % hydrochloric acid to obtain a polymer. The results are shown in Table 42. The content of the unsaturated carboxylic ester in the polymer as measured by NMR analysis was 0.77 mol %.

    ##STR00031##

    TABLE-US-00004 TABLE 4 Is there a spherical or Polymerization sphere-like polymer Activity 10.sup.6 g .Math. Mw in the copolymer?/ No. Complex mol.sup.?1(Ni) .Math. h.sup.?1 (?10.sup.4) PDI Particle size (mm) Example 32 Ni12 10.99 7.82 3.72 Yes/0.62 Example 33 Ni12 5.27 12.72 4.03 Yes/0.83 Example 34 Ni12 7.27 14.18 3.95 Yes/0.74 Example 35 Ni12 3.62 32.28 3.23 Yes/1.82 Example 36 Ni12 4.82 14.02 3.62 Yes/1.24 Example 37 Ni12 4.24 5.13 3.26 Yes/0.92 Example 38 Ni12 4.82 15.33 4.14 Yes/4.32 Example 39 Ni13 11.20 33.71 3.43 Yes/0.98 Example 40 Ni14 12.71 31.21 3.14 Yes/0.96 Example 41 Ni15 10.72 11.22 3.27 Yes/0.80 Example 42 Ni16 5.02 10.31 3.74 Yes/2.32 Example 43 Ni17 9.28 32.44 3.27 Yes/1.89 Comp. Ex. 5 Ni12 3.17 10.72 4.03 No Comp. Ex. 6 A 2.12 16.72 3.43 No

    [0340] It can be seen from Table 4 that when the catalysts of the invention catalyze the copolymerization of ethylene with an unsaturated carboxylic ester, they exhibit higher polymerization activities. The copolymerization activities of the catalyst systems of the invention are higher than those of comparative examples and can be up to 12.7?10.sup.6 g.Math.mol.sup.?1(Ni).Math.h.sup.?1. In addition, by adjusting polymerization conditions, copolymer products with good particle morphology can be obtained. Spherical and/or sphere-like polymers with good shape are directly prepared without subsequent processing steps such as granulation, and the resultant polymer products are not prone to fouling in the reactor and are convenient for transportation.