Synthesis and properties of syndiotactic 1,2‐polybutadiene catalyzed by iron catalyst with phosphate as additive

Abstract

Abstract1,2 Syndiotactic polymerization of butadiene is accessible by iron catalysts prepared from commercially available iron sources, trialkylaluminum with additional phosphate as additive. The catalyst formation is quite robust in terms of handling and stability under polymerization conditions. Activity equal to 115 kg (polymer)/mol(Fe)·h is achieved at 10,000 equiv. of monomer relative to the catalyst loading in 2 h at 50°C. The resultant polymer possesses 1,2 incorporation up to 80.2–93.1% with syndiotactic configuration (rrrr) of 40.2–85.2%. Crystallinity of polymers can be also tuned over a wide range degree from weak (2.1%) to high crystallinity (68.2%) by varying catalyst component feeding, enabling potential application as both rubber and resin. The higher activity of iron catalyst is preferred at hydrocarbon solvent n‐hexane, n‐heptane or toluene, higher temperature as well as trialkylalumium, such as tri‐iso‐butylaluminum, tri‐ethylaluminum, and tri‐methylaluminum as cocatalyst. Significant stereospecificity stability to variation for monomer concentration, type of alkylaluminum and temperature is also found. The high activity and 1,2‐stereoselectivity featured with these thermal robust iron catalysts sheds light on the significance of additive on regulating stereo‐polymerization promoted by conventional Ziegler–Natta catalysts. These features collectively could offer advantages for application in industry production of 1,2‐syndiotactic polybutadiene.