Synergistic effect of amine and borane in immobilized metallocene catalysts on ethylene polymerization

The effect of incorporating amines and borane into the supported metallocene catalyst systems was investigated for the polymerization of ethylene and copolymerization of ethylene-1-hexene. Two methods, the conventional method and the one-pot method, were employed to prepare immobilized metallocene catalysts. The synthesized catalysts underwent characterization using scanning electron microscopy (SEM), elemental analysis (EA), inductively coupled plasma (ICP) analysis, and X-ray photoelectron spectroscopy (XPS). The results revealed that the inclusion of polyethyleneimine (PEI) increased the Zr content in the catalyst and yielded polyethylene with higher molecular weight. PEI also exhibited the ability to enhance the comonomer response of supported metallocene catalysts. Additionally, the immobilization of both PEI and borane demonstrated a significant improvement in polymerization activity. XPS analysis demonstrated the electronic effects of amines and borane on the catalyst, indicating enhanced anionic properties of methylaluminoxane and the formation of cationic zirconocenium species. These findings suggest that the presence of PEI and borane promotes the formation of more active metallocene sites for ethylene polymerization.