Abstract:
The kinetics of anionic polymerization of polystyryl salts with various gegen ions have been
investigated spcctrophotomctrically in 1,2-dimethoxyethanc (DME) + benzenc mixtures at 25QC.
The behaviour of two types of polymers, viz. one- and two-ended polymers, was studied for sodium
and caesium salts. The two-ended sodium salt is as reactive as the one-ended salt, whereas the two-
ended caesium salt is less reactive than the one-ended salt. The conductance of the two-ended
sodium salt is smaller than that of the one-ended, whereas the conductance of the two-ended caesium
salt is larger than that of the one-ended salt. The ion-pair rate constants k'p in the DME +benzene
(50 : 50) mixture are 360, 182 and 90 dm3 mol-1 s-1 for the sodium, potassium and caesium salts.
The dissociation constants K are 4.7 x IO-10, 1.3 x 1O~10 and 3.5 x IO-13 mol dm-3 for the sodium,
potassium and caesium salts. The free ion rate constant kp is 9-10 x 104 dm3 mol-1 s"' for these
salts. The contribution of the intra-molecular triple-ion was observed for the two-ended living
polystyrene and the rate constant fcp'(c) of this ionic species is ~1000dm3 mol-1 s-1, practically
independent of solvent, and; is smaller than the rate constant of the solvent-separated intcrmolccular
triple ion (Ap'~1.2x 10s dm3 mol-1 s-1).
