Detailed studies of anionic polymerization of sodium and cesium salts of living polystyrene in dimethoxyethane (DME) led to the absolute rate constants of propagation for the -S-,Na+ and -S-,Cs+ ions pairs as well as for the free -S-ions. These constants were determined over a temperature range +SO to -60°, providing therefore the necessary data for the calculation of the respective activation energies. The Arrhenius plot of the propagation constant of the -S-,Na+ ion pair produced a curve with a maximum at 0". This behavior was fully rationalized by assuming the presence of contact and solvent-separated -S-,Na+ ion pairs. An analysis of the data led to the absolute rate constant of the solvent-separated ion pair. The thermodynamics of the dissociation and solvation processes involving ion pairs was fully elaborated.etailed studies of the kinetics of anionic polym-D erization revealed that its propagation involves ion pairs and free Living polymer systems offer many advantages in such investigations. Apart from an increase in the chain length, which does not affect its rate of growth, the initial and final states of the propagating species remain the same.-S-,Na-+ S --S-,Na+ i.e., the sodium salt of an n-meric living polystyrene (-S-,Na+) is converted on the addition of a styrene molecule (S) into an ( n + 1)-meric specie. Therefore, the progress of the reaction does not disturb the equilibrium established between the ion pairs and free ions or between the different types of ion pairs.
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