Abstract
The kinetics of anionic polymerization of polystyryl salts with various gegen ions have been investigated spectrophotometrically in 1,2-dimethoxyethane (DME)+ benzene mixtures at 25°C. 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 × 10–10, 1.3 × 10–10 and 3.5 × 10–12 mol dm–3 for the sodium, potassium and caesium salts. The free ion rate constant k″p is 9–10 × 104 dm3 mol–1 s–1 for these salts. The contribution of the intra-molecular triple-ion was observed for the two-ended living polystyrene and the rate constant k″′p(c) of this ionic species is ∼1000 dm3 mol–1 s–1, practically independent of solvent, and is smaller than the rate constant of the solvent-separated intermolecular triple ion (kt′p∼1.2 × 105 dm3 mol–1 s–1).
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