A one-shot activating reagent of neodymium carboxylate for highly cis-1,4 specific butadiene polymerization

Abstract

A streamlined catalytic system to produce high-cis polybutadiene (cis-PBD), consisting of neodymium carboxylate and a halogenated MAO-derived activator, was developed. Halogenated MAO was synthesized via the replacement of methyl groups of commercial MAO with chlorides using BCl₃. The polymerization of butadiene under optimal conditions (Al/Nd = 50 and Cl/Nd = 2.1) at 25 °C resulted in nearly complete conversion, producing cis-PBD with a high molecular weight (M_n > 10⁵), a narrow molecular weight distribution (Đ ∼ 2), and a high cis-content (>98%). Cl incorporation into both the MAO framework and the active species was confirmed by X-ray total scattering analysis, which showed that halogenated MAO functions as both an alkylating and halogenating agent for the neodymium salt. Halogenated MAO may replace traditional ternary cocatalyst systems, giving a simpler catalyst composition and higher stereoregularity.