The dynamics of living polymerization of styrene was studied with alkyllithium/potassium alkoxide as bimetallic initiator and cyclohexane as solvent. It was found that the apparent propagation rate constants (kap )increased greatly with little increasing of K/Li ratios and in linear relationships with the concentrations of potassium alkoxide ([POK])when K/Li ratios were lower that 0.1. And the slopes of kap-[ROK] lines increased with the decreasing of alkyllithium concentrations. This dynamics feature can not be explained quantitatively by the ordinary association dynamics model which ignored the cross-association between the propagation species with different metallic ion. In this paper

a new dynamics model on cross-association concept was established and the dynamics feature of living polymerization of styrene can be interpreted satisfactorily.The propagation rate constant of potassium species(kk) and the constant group

(K1/2)0.5/K3

of dissociation constants of cross-association species (K3) and lithium species (K1) were derived by curve fitting and led to values of 7.1×103(mol/L)-1min-1and 67(mol/L)-0.5respectively at a polymerization temperature of 50℃.