Divinylidene compounds and their role as key compounds for the synthesis of blockcopolymers

Divinylidene compounds with isolated double bonds of the type magnified image are quantitatively transformed into soluble dilithio organic compounds with sBuLi and may be used as bifunctional initiators for the anionic polymerization of butadiene (B) and subsequently styrene (S). Beside the expected SBS block copolymers also SB block copolymers are obtained because of partial termination of the dilithio compounds. By means of GPC analysis of the reaction compounds, i.e., of the homopolybutadiene, the blockcopolymers and the homopolystyrene after oxidative degradation using dual detection it is proved that the bifunctional species because of intramolecular association adds the monomer with significantly lower rate than the monofunctially growing species. Choosing suitable conditions the rate differences may be minimized.