The Influence and Mechanism of Ligand Steric Hindrance and Electronic Effects on the Ring-Opening Metathesis Polymerization of Polycyclopentene under Tungsten Complex

Polycyclopentene rubber has attracted attention due to its unique ring-opening metathesis polymerization (ROMP) mechanism, which endows it with a range of excellent properties, including recyclability and structural controllability. In order to facilitate the production of polycyclopentene, a tungsten olefin metathesis catalytic system was developed. The influence of ligand steric hindrance and electronic effects on the reaction was investigated through kinetic experiments and density functional theory (DFT) calculations. The results show that increased ligand steric hindrance enhances reaction stability, while the electro-withdrawing group on the ligand accelerates catalyst activation. Additionally, a ligand "release-return" mechanism for polymerization initiation was proposed. The polycyclopentene's thermal properties and stereoregularity were explored.