Synergistic Regulation of Hydrogen Partial Pressure and Ligand Effects on the Metallocene‐Catalyzed Synthesis of Polyethylene Wax

Polyethylene wax (PEW) produced by metallocene catalysts has attracted increasing interest due to its excellent physicochemical properties. Research on using constrained geometry catalysts (CGCs), a class of metallocene catalysts, to control the molecular weight of PEW by modifying ligand steric and electronic effects has rarely been mentioned. In this work, five titanium‐based CGC‐type metallocene catalysts with systematically tuned ligand architectures were synthesized and evaluated for ethylene polymerization toward PEW. The combined influences of ligand steric/electronic properties and H 2 partial pressure on catalytic behavior and PEW characteristics were investigated. The results reveal that steric and electronic effects synergistically regulate chain‐transfer and chain‐growth processes. CGCs with reduced steric hindrance and stronger electron‐donating ligands promote chain transfer, affording low‐molecular‐weight PEW with broader molecular weight distributions. In contrast, increased steric bulk and/or weakened electron donation suppress chain transfer and delay chain termination, producing higher‐molecular‐weight PEW with narrower dispersity. Notably, the [t‐BuNSiMe 2 (Me 4 Cp)]TiMe 2 /MAO system at an H 2 partial pressure of 0.9 MPa delivered PEW with M n = 0.24×10 4 g·mol − 1 , PDI = 2.28, and a melt flow index of 13.83 g·10 min − 1 . This work demonstrates that CGC ligand engineering combined with H 2 regulation provides an effective strategy for the directional synthesis of PEW with tailored properties.