Anionic Polymerization of Isoprene at Low Concentrations of Polyisoprenyllithium

The kinetics of polymerization of isoprene with n-butyllithium initiator was investigated in n-hexane solution over an extended concentration range of poly-organolithium. The propagation reaction was found to be first-order with regard to monomer and half-order with respect to chain anion concentration. The degree of chain anion aggregation, in the association equilibrium between active single chains and inactive associated chains, was concurrently scrutinized. The evidence accrued from the studies indicates that the associated chains exist only as binary aggregates. These experimental findings are in concert with those results obtained at higher concentrations of polyorganolithium.