Linear/branched Block Polyethylene Produced by a-Diimine Nickel(Ⅱ)Catalyst and Bis(phenoxy-imine)Zirconium Binary Catalyst System in the Presence of Diethyl Zinc

In order to promote development of linear/branched block polyethylenes based on new catalytic systems,we synthesized a novel a.dimine nickel(Ⅱ)complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-Naryl structures.The activity of a-dimine nickl(Ⅱ)catalyst was 3.02x10^(6)g-mol_(ni)^(-1)·h^(-1) at 70℃,and resultant polyethylene possessed 135/1000C branches.The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the a-dimine nicke(Ⅱ)complex/bis(phenoxy-imine)zirconium in the presence of diethyI zinc.With the addition of ZnEtz(from 0 to 400),the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks.The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained vla adjusting ZnEt;equiv.and molar ratio of two catalysts.In addition,the branching degree of the polyethylene increased from 13/1000C to 56/1000 with the increase of the proportion of a dimine nickel(Ⅱ)catalyst.Using this binary catalyst system,the reaction temperature of chain shutting polymerization can be carried out at 70℃,which is more conducive to industrial application.

Ethylene Polymerization with Novel Phenoxy-imine Catalysts Bearing 4-Vinylphenyl Group

This contribution reports ethylene polymerization behavior of titanium complexes incorporating bis（phenoxyimine） ligands. Six phenoxy-imine Ti（IV） complexes {6-R^1-2-[CH=N（2,6-difluoro-3,5-diR^2-4-R^3Ph）]C6H30}2TiCl2 （1： R^1 = H, R^2 = H, R^3 = H; 2： R^1 = H, R^2 = H, R%3 = 4-vinylphenyl; 3： R^1 = CH3, R^2 = H, R^3 = H; 4： R^1 = CH3, R^2 = H, R^3 = 4-vinylphenyl; 5： R^1 = CH3, R^2 = F, R^3 = H; 6： R^1 = CH3, R^2 = F, R^3 = 4-vinylphenyl） have been synthesized and evaluated for ethylene polymerization using dried MAO （simplified as DMAO） as cocatalyst. An obvious catalytic heterogeneity of Cat 2 （Complex 2/DMAO） towards ethylene polymerization was observed, which was illustrated by decreased activity, multi- modal molecular weight distribution and partially improved particle morphology comparing with Cat 1. Moreover, Cat 3 exhibits ＂living＂ characteristics in the process under certain conditions （25 ~C, less than 20 min）. Otherwise, the moderate to high ethylene polymerization activity of ca. 105-106 g PE/（mol Ti＇h） and high molecular weight （Mw = 105-106） of polyethylene can be obtained by changing the skeleton structure of these complexes.

SYNTHESES,CHARACTERIZATION AND ETHYLENE POLYMERIZATION OF HALF-SANDWICH GROUP IV METAL COMPLEXES WITH TRIDENTATE [O,N,S] LIGANDS

A series of half-sandwich group IV metal complexes with tridentate monoanionic phenoxy-imine arylsulfide [O-NS] ligand [2-Bu^t4-Me-6-（（2-（SC6H5）C6H4N = CHC6H2O）]- （La） and dianionic phenoxy-amine arylsulfide [O-N-S] ligand [2-Bu^t4-Me-6-（（2-（SC6H5）C6H4N-CH2C6H2O）]2- （Lb） have been synthesized and characterized. Lb was obtained easily in high yield by reduction of ligand La with excess LiAlH4 in cool diethyl ether. Half-sandwich Group Ⅳ metal complexes CpTi[O-NS]Cl2 （1a）, CpZr[O-NS]Cl2 （1b）, CpTi[O-N-S]Cl （2a）, CpZr[O-N-S]Cl （2b） and CpZr[O-N-S]Cl （2c） were synthesized by the reactions of La and Lb with CpTiCl3, CpZrCl3 and Cp ZrCl3, and characterized by IR, ^1H-NMR, ^13C-NMR and elemental analysis. In addition, an X-ray structure analysis was performed on ligand Lb. The title Group IV half-sandwich bearing tridentate [O,N,S] ligands show good catalytic activities for ethylene polymerization in the presence of methylaluminoxane （MAO） as co-catalyst up to 1.58 × 10^7 g-PE.mol-Zr-1.h-1. The good catalytic activities can be maintained even at high temperatures such as 100 ℃ exhibiting the excellent thermal stability for these half-sandwich metal pre-catalysts.