Kinetics of the anionic polymerization of styrene in benzene. Effect of the alkali-metal counter-ion

Abstract

The propagation reaction in the anionic polymerization of styrene has been studied with the counter-ions, Na, K, Rb and Cs. In the range of active-centre concentration between 10^–3 and 10^–5M, with sodium the ion-pairs are entirely associated, with caesium the ion-pairs are not associated, while potassium shows intermediate behaviour. Absolute ion-pair propagation constants could be measured for polystyryl potassium, rubidium and caesium. The equilibrium constant for association of ion-pairs was determined for polystyryl potassium, together with the heat and entropy of association.