| Popis: |
Polyolefins account for over half of global plastic production. The incorporation of polar functionalities can provide value-added polyolefins with desirable material properties and potential degradability. To achieve this, coordination copolymerization of ethylene and fundamental polar comonomers by transition-metal catalysts is the most direct, economical, and environmentally friendly method. Though it has been pursued for decades, the catalyst performance (e.g. activity, thermal stability) is still far below practical thresholds. The major issue is the "polar monomer problem": coordination of the polar group in the comonomer to the metal center competes with vinyl coordination, a prerequisite for the monomer enchainment (chain propagation). This thesis describes mechanism-driven developments of industrially applicable molecular catalysts toward addressing the "polar monomer problem", with a focus on nickel catalysts for ethylene/acrylate copolymerization. |
