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

摘要

In a former article the dissociation of organolithium salts due to pi-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 pi-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 l,3-di(l-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.