New Ways of Controlling the Molecular Mass Characteristics and Distribution of Branches for Polyethylene Synthesized over Supported Catalysts Containing Fe(II) Bis(imino)pyridyl and Ni(II) Bis(imine) Complexes

Data on the ways of controlling the molecular structure of polyethylene (PE) synthesized over the supported catalysts containing Fe(II) bis(imino)pyridyl (LFeCl₂) and Ni(II) bis(imine) (*LNiBr₂) complexes immobilized on a silica gel modified with aluminum oxide (SiO₂(Al)) are presented. Linear polyethylene with different molecular masses and a controllable molecular weight distribution (MWD) is synthesized by varying the conditions of polymerization on LFeCl₂/SiO₂(Al) catalysts. Ethylene homopolymerization over *LNiBr₂/SiO₂(Al) catalysts results in branched polyethylene with molecular mass and thermophysical characteristics close to that of low density polyethylene synthesized by ethylene copolymerization with α-olefins over supported metallocene and Ziegler type catalysts. A way for designing supported bicomponent catalysts containing LFeCl₂ and *LNiBr₂ complexes immobilized on an SiO₂(Al) support for the targeted synthesis of polyethylene with a required molecular structure is proposed. Examples are given for the synthesis of linear polyethylene with a bimodal MWD on a bicomponent supported catalyst containing two different LFeCl₂ complexes, the synthesis of polyethylene with a controllable distribution of branches on a bicomponent catalyst prepared via the immobilization of LFeCl₂ and *LNiBr₂ complexes on a SiO₂(Al) support, and the modification of a chromium oxide catalyst with LFeCl₂ complex for controlling the molecular mass and branch distributions in synthesized polyethylene are given.