Kinetics of the Anionic Polymerization of Buta‐1,3‐diene Considering Different Reactivities of the cis, trans and vinyl Structural Units

The anionic solution polymerization of buta-1,3-diene was modeled, considering the reactivity of the active sites to be different due to varying geometric configurations. With the first-order Markov model, expressions for the fraction of active sites and dyad distribution were obtained. The rate constants were determined by fitting to the conversion and dyad experimental data using the nonlinear least squares method. The kinetic model shows that the microstructure and the dyads do not depend on initiator and butadiene concentration but only on rate constants. Without a modifier, the butadiene addition mechanism is entropic; with a modifier, the mechanism changes to entropic-enthalpic.