Catalytic behavior of Co(II) complexes with 2-(benzimidazolyl)-6-(1-(arylimino)ethyl)pyridine ligands on isoprene stereospecific polymerization

Polymerization behaviors of isoprene under different polymerization conditions with 2-(1-methyl-2-benzimidazolyl)-6-(1-(arylimino)ethyl) pyridine cobalt(II) dichloride and ethylaluminum sesquichloride or diethylaluminum chloride catalyst systemwere evaluated. The effects of temperature, solvents, [Al]/[Co] molar ratio, and the structure of cocatalysts on the catalyst activityand the characteristics of polyisoprenes (PIs) were investigated and optimum conditions for synthesizing stereoselective PIs wereobtained. The results showed that pre-catalyst activity was strongly influenced by polymerization temperature, [Al]/[Co] molar ratioand solvents, and the kinds of solvents and cocatalysts affected the microstructures of PIs greatly. V C 2013 Wiley Periodicals, Inc. J. Appl.Polym. Sci. 2014, 131, 39703. KEYWORDS: catalysts; properties and characterization; rubberReceived 18 December 2012; accepted 26 June 2013DOI: 10.1002/app.39703INTRODUCTION Great progress has been achieved in polyolefin industry with thedevelopment of coordination polymerization catalysts, whichplayed an important role in control of polymer stereoregular-ities. Among the coordination polymerization catalysts, tradi-tional Ziegler-Natta catalysts