Kinetic study of the initiation reaction by a dilithium initiator used for the preparation of ABA triblock copolymers in non-polar medium

The kinetics of the reaction of the bifunctional lithium initiator, Li-DIB-Li, with DPE was studied. It was shown that the kinetic order of this reaction with respect to the reactive ends of the dilithium initiator is close to zero, indicating a rather high degree of aggregation of the dilithium initiator. Possible structures of these highly aggregated species are illustrated by DFT quantum-chemical calculations and their relative stabilities are analyzed. It is concluded that the solubilization through breaking up of long intermolecular aggregates of dilithium initiator chains into small soluble ones by complexation with durene is certainly as important or more than the dissociation of the active centers of the dilithium initiator, as originally thought.