Abstract
A series of Ti(Ⅳ)dichloride and dialkoxide complexes with phenoxyimine ligands containing fluorinated and nonfluorinated aliphatic imine fragments have been synthesized.The molecular structures of complexes 1 and 4 were established by single-crystal X-ray diffraction studies.The complexes adopt a distorted octahedral coordination structure around the titanium atom and two oxygen atoms are situated in trans position while two nitrogen atoms and two outgoing ligands(Cl or iPrO)are situated in cis position.Effect of activators(MMAO-12 and combinations EtnAlCl3-n+Bu2Mg)and outgoing ligand(Cl or iPrO)nature on the catalytic activity and properties of the resulting polymers was studied.The Ti complexes,despite the nature of the outgoing ligands(Cl or iPrO)in the presence of Al/Mg activators,was found to display a high ethylene polymerization activity in the range 1600-3830 kgpolymer·molTi-1·h-1·atm-1 with a viscosity average molecular weight(Mv)value in the range 1.1x106-7.1x106 Dalton(Da).The resulting UHMWPE can be processed by a solventless method into high-strength and high-modulus oriented films.The rheological characteristics of a polymer melt have been studied.The absence of a cross-over point did not allow to compare the values of the molecular weight distribution of polymers obtained on fluorinated and non-fluorinated pre-catalysts,however,the estimation of the entanglement density is in good agreement with the mechanical characteristics of oriented films.Upon activation with methylalumoxane,the activity of the complexes decreased very significantly;however,a polymer with a molecular weight of about 12 million Da was obtained.In the process of ethylene/octene-1 copolymerization,fluorine-containing precatalysts showed a clear advantage over non-fluorinated analogues both in activity and in comonomer content.
基金项目
Russian Science Foundation(22-23-00578)
Ministry of Science and Higher Education of the Russian Federation using the equipment of Center for molecular composition s(075-00697-22-00)
Ministry of Science and Higher Education of the Russian Federation employing the equipment of Center for molecular compositi()
NETL
NSTL
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