Initiation of Styrene Retarded Anionic Polymerization Using the Combination of Lithium Alkoxides with Organometallic Compounds

The possibility to initiate styrene retarded anionic polymerization in hydrocarbon solvents from bimetallic systems based on lithium alkoxide and metal-alkyl derivatives like trialkylaluminum or dialkylmagnesium was investigated. The combination of the two organometallic compounds, individually inactive, affords an active initiating system which can be an alternative to alkyllithium initiators. Activation involves a ligand exchange inside the bimetallic complex, thus in situ forming an alkyllithium compound complexed with a new alkoxymetal-alkyl derivative. The kinetics and extent of the ligand exchange process are highly dependent on the nature of both the ligand and the metal, magnesium alkyls being much more efficient than aluminum ones. The influence of the nature of both the lithium alkoxide and the metal-alkyl derivatives on the initiation efficiency and retardation of styrene polymerization was studied.