Work

Advanced Polyethylene Wax via Zinc‐Enhanced Metallocene Catalysis: Insights Into Molecular Weight Regulation Mechanisms

Year: 2025

Type: article

Abstract: ABSTRACT High‐end polyethylene wax (PE‐WAX) synthesized via ethylene polymerization is increasingly demanded for its superior physicochemical properties. Precise regulation of molecular weight and microstructure by metallocene catalysts remains a critical research focus. Herein, eight structurally distinct metallocene catalysts are systematically evaluated, with three optimal systems (M3, M4, M8) selected based on structure‐activity relationships. Zinc‐mediated chain transfer mechanisms and process optimization (Zn/Zr ratios, catalyst loading, temperature, pressure) are investigated through integrated experimental and density functional theory (DFT) studies. ZnEt 2 addition effectively reduces molecular weights to the PE‐WAX range (1000–10 000 g/mol), while revealing catalyst‐dependent sensitivities: M8 demonstrates exceptional zinc responsiveness due to optimal electronic‐steric synergy (smallest HOMO(Catalyst)–LUMO(ZnEt 2 ) gap ΔE = 0.094 eV, longest Zr‐C bond = 2.30 Å, shortest Zn‐C distance = 4.84 Å), enabling efficient chain transfer. Pressure exerts significant control over molecular weight (M8: 7.8 × 10 3 –2.26 × 10 4 g/mol) and branching density (1.3–9.1/1000C). DFT calculations confirm reduced kinetic barriers originate from synergistic electronic effects and spatial accessibility, establishing M8 as the premier catalyst for tunable PE‐WAX production.

Source: Macromolecular Reaction Engineering

DOI: 10.1002/mren.70003