POS1-0180
Cocatalyst design for controlled olefin and diene polymerization with single-site catalysts: toward simplified catalytic processes
Topic
S1. Polymer Synthesis
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
YU JIA (Hiroshima University)
Co-Author(s)
Abstract
Olefin polymerization using single-site catalysts has enabled precise control over polymer microstructures, including molecular weight, branching density, regioselectivity, and stereoregularity. However, conventional strategies often rely on elaborate ligand design or multicomponent catalyst systems, which increase synthetic complexity and limit practical applicability. Our approach focuses on cocatalyst design as an alternative strategy for controlling polymerization behavior with single-site catalysts while simplifying catalytic processes.
In this lecture, we will present three successful examples following the strategy. First, halogenated methylaluminoxane (MAO) was prepared by the reaction of commercial MAO with main-group halogenating reagents BCl3 and applied to nickel-diimine-catalyzed ethylene polymerization. The modified MAO significantly suppressed chain walking, affording polyethylene with reduced branching density and higher linearity without changing the ligand structure of the nickel catalyst. Second, the same concept was extended to neodymium carboxylate-catalyzed butadiene polymerization. Halogenated MAO functioned as a one-shot activator, serving as both an alkylating and halogenating reagent, and enabled highly cis-1,4-specific polybutadiene synthesis with a simplified catalyst composition compared with conventional ternary systems. Third, a MgCl2-based heterogeneous cocatalyst incorporating internal donors was developed for nickel-diimine-catalyzed ethylene and propylene polymerization. This system combined single-site catalyst characteristics with Ziegler-Natta-type cocatalyst design, allowing modulation of chain walking and regioselective insertion in a heterogeneous catalytic environment. These studies demonstrate that cocatalysts are not merely activators but key design elements for controlling active-site environments, polymerization behavior, and polymer microstructures.
In this lecture, we will present three successful examples following the strategy. First, halogenated methylaluminoxane (MAO) was prepared by the reaction of commercial MAO with main-group halogenating reagents BCl3 and applied to nickel-diimine-catalyzed ethylene polymerization. The modified MAO significantly suppressed chain walking, affording polyethylene with reduced branching density and higher linearity without changing the ligand structure of the nickel catalyst. Second, the same concept was extended to neodymium carboxylate-catalyzed butadiene polymerization. Halogenated MAO functioned as a one-shot activator, serving as both an alkylating and halogenating reagent, and enabled highly cis-1,4-specific polybutadiene synthesis with a simplified catalyst composition compared with conventional ternary systems. Third, a MgCl2-based heterogeneous cocatalyst incorporating internal donors was developed for nickel-diimine-catalyzed ethylene and propylene polymerization. This system combined single-site catalyst characteristics with Ziegler-Natta-type cocatalyst design, allowing modulation of chain walking and regioselective insertion in a heterogeneous catalytic environment. These studies demonstrate that cocatalysts are not merely activators but key design elements for controlling active-site environments, polymerization behavior, and polymer microstructures.
