The anionic bulk polymerization of α-methylstyrene-II. Kinetic study of the propagation

Abstract A kinetic study of the anionic bulk polymerization of α-methylstyrene initiated with tert -butyllithium ( t -BuLi) in presence of N , N , N ′, N ′-tetramethylethylenediamine (TMEDA) has been performed. Kinetic measurements have been carried out using dilatometry at 25° and 40° up to 37% conversion. The reactivity of the system is found to be a function of the ratio r = [TMEDA]/[ t -BuLi]. The apparent rate constant decreases with increasing values of r for r r > 1. The results are explained by the presence of three different active species, viz. contact ion-pairs contact ion-pairs stretched solvated with a TMEDA molecule, ion-pairs stretched by n TMEDA molecules. When the temperature is raised to 62°, the active centres become unstable and cyclic oligomers are formed.