Modeling the kinetics of anionic polymerization in cyclohexane as a non-complexing solvent

In this work it is presented a model of alkyllithium initiated anionic polymerization. The model was developed from the balance of living polymer chains of each chain length, taking into account the participation of molecular aggregates of lithium compounds in initiation and propagation reactions. The model was applied to styrene polymerization in cyclohexane, where the known but not explained acceleration of initiation reaction takes place. The well established reaction order respect to polystyryllithium in propagation reaction allowed some simplification of the model. A more simplified model of three parameters was also developed by using apparent kinetic constants. As part of the work, the apparent propagation constants were determined experimentally and are reported in the Arrhenius equation form. The remainder kinetic parameters used in the model were assumed or fitted to experimental data and are described into the work. The model allows explaining acceleration of the initiation reaction and experimental data of molecular weight averages (M(n), M(w) and M(z)) during the polymerization. The three-parameter model was only able to explain the acceleration of initiation reaction and monomer conversion data.