Synthesis of syndiotactic cis-1,4-polypentadiene by using ternary neodymium-based catalyst

Stereoselective polymerization of 1,3-pentadiene (1,3-PD) by using the ternary catalyst system neodymium versatate (Nd(vers)3)/alkylaluminium/Al(i-Bu)2Cl was examined. Both homogeneous and heterogeneous catalyst systems prepared in the presence or absence of 1,3-PD monomer during catalyst preparation were employed for 1,3-PD polymerization. The effects of the type of alkylaluminium, [Al]/[Nd] molar ratio, and polymerization temperature on polymerization behaviours were investigated in detail. Syndiotactic polypentadienes with cis-1,4 content ranged from 48.4% to 83.2% depending on polymerization conditions were obtained. The compounded polypentadiene vulcanizate showed fairly good mechanical properties, demonstrating 1,3-PD and the resultant polypentadiene are both qualified as a conjugated diene monomer and a synthetic rubber for practical application, respectively.