Living anionic polymerization of butadiene

Polymer Synthesis and Characterization. This topic has been extensively discussed in preceeding papers.(2,23,24) However, we will briefly outline the preparative route. The block copolymers were synthesized via the sequential addition method. "Living" anionic polymerization of butadiene, followed by isoprene and more butadiene, was conducted using sec-butyl lithium as the initiator in hydrocarbon solvents under high vacuum. Under these conditions, the mode of addition of butadiene is predominantly 1,4, with between 5-8 mole percent of 1,2 structure.(18) Exhaustive hydrogenation of polymers were carried out in the presence of p-toluenesulfonylhydrazide (19,25) in refluxing xylene. The relative block composition of the polymers were determined via NMR. 

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