Synthesis and development of a dilithium initiator and its use for the preparation of ABA-block copolymers in non-polar medium: the use of π-complexing additives

In a former article the dissociation of organolithium salts due to π-complexing additives is described. Durene and tetraphenylethylene tend to break up at least partly the dimeric structure of polystyryllithium in non-polar solvents, as well as higher aggregates such as those formed by polybutadienyllithium. In this research these π-complexing additives are used to break up a similar association, i.e. the formation of tridimensional insoluble multifunctional initiator mixtures, when a bifunctional initiator is synthesized, using a precursor and a 2-fold excess of butyllithium. As the precursor mainly 1,3-diisopropenylbenzene (m-DIB) is used, but also 1,3-di(1-phenylethenyl)benzene (PEB) is examined. Subsequent addition of styrene in the presence of durene and tetraphenylethylene gives satisfying results in the synthesis of SBS-triblock copolymers.