文献类型：期刊文献

英文题名：Synergistic Regulation of Hydrogen Partial Pressure and Ligand Effects on the Metallocene-Catalyzed Synthesis of Polyethylene Wax

作者：Huang, Miao[1];Chu, Qingyun[1];He, Xuelian[1];Tian, Zhou[1]

机构：[1]East China Univ Sci & Technol, Shanghai Key Lab Multiphase Mat Chem Engn, Shanghai, Peoples R China

年份：2026

卷号：227

期号：11

外文期刊名：MACROMOLECULAR CHEMISTRY AND PHYSICS

收录：;EI(收录号：20262420878754);WOS:【SCI-EXPANDED(收录号:WOS:001787722600001)】；

语种：英文

外文关键词：ethylene polymerization; melt flow index; metallocene catalysts; polyethylene wax

摘要：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 H2 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-BuNSiMe2(Me4Cp)]TiMe2/MAO system at an H2 partial pressure of 0.9 MPa delivered PEW with M n = 0.24 & times;104 g & centerdot;mol- 1, PDI = 2.28, and a melt flow index of 13.83 g & centerdot;10 min- 1. This work demonstrates that CGC ligand engineering combined with H2 regulation provides an effective strategy for the directional synthesis of PEW with tailored properties.