Novel Methylaluminoxane-Activated Neodymium Isopropoxide Catalysts for 1,3-Butadiene Polymerization and 1,3-Butadiene/Isoprene Copolymerization

The homo- and copolymerizations of 1,3-butadiene and isoprene are examined by using neodymium isopropoxide [Nd(Oi-Pr)(3)] as a catalyst, in combination with a methylaluminoxane (MAO) cocatalyst. In the homopolymerization of 1,3-butadiene, the binary Nd(Oi-Pr)(3)/MAO catalyst works quite effectively, to afford polymers with high molecular weight ((M) over bar (n) approximate to 10(5) g mol(-1)), narrow molecular-weight distribution (MWD) ((M) over bar (w)/(M) over bar (n) = 1.4-1.6), and cis-1,4-rich structure (87-96%). Ternary catalysts that further contain chlorine sources enhance both catalytic activity and cis-1,4 selectivity. In the copolymerization of 1,3-butadiene and isoprene, the copolymers feature high (M) over bar (n), unimodal gel-permeation chromatography (GPC) profiles, and narrow MWD. Most importantly, the ternary Nd(Oi-Pr)(3)/MAO/t-BuCl catalyst affords a copolymer with high cis-1,4 content in both monomer units (>95%).