Anionic polymerization with alkaline earth counterion. III. Aging of oligo- and polystyryl-barium and -strontium in THF

The self-deactivation of polystyryl-barium and polystyryl-strontium in tetrahydrofuran (THF) results essentially from protonation by the solvent. The deactivation constant k_d of this reaction is independent of carbanion concentration, length, and functionality of chains. Relations of k_d with temperature are: polystyryl-barium: k_d = 6.25 × 10⁷ exp(-18,900/RT) sec^?1; polystyryl-strontium: k_d = 4.1 × 10⁶ exp(?16,000/RT) sec^?1. The self-deactivation of α,ω-dicarbanionic oligostyryl-barium is a nonrandomlike reaction. Residual living oligomers are left dicarbanionic even if an important deactivation occurs.