Efficiencies of various metallocene/reducing agent catalyst systems in the hydrogenation of polystyrene-b-polybutadiene-b-polystyrene block copolymers

摘要

Various metallocenes, including bis(η5-cyclopentadienyl)cobalt, bis(η5-cyclopentadienyl)nickel, and bis(η5-cyclopentadienyl)titanium dichloride, combined with various reducing agents, including n-butyllithium, phenyllithium, and triethylaluminum, have been evaluated for their catalytic efficiencies in the hydrogenation of polystyrene-b-polybutadiene-b-polystyrene (SBS) block copolymer. The efficiencies were determined by monitoring the extent of saturation of double bonds on the polybutadiene segment of the copolymer using FTIR and 1H-NMR spectroscopy. The cobaltocene-butyllithium catalyst system was found the most active. The effects of H2 pressure and the ratio of n-butyllithium to cobaltocene ratio on the hydrogenation efficiency were also investigated.