Kinetics of Anionic Polymerization of ε-Caprolactone (εCL). Propagation of Poly-ε=CL-K⁺Ion Pairs

Kinetics of the anionic polymerization of ε-caprolactone (εCL) initiated with (CH3)3SiO−K+ and carried out in THF solution has been studied in the temperature range from 0 to 20°C by using a calorimetric method. From the kinetic results and from conductometric measurements of the dissociation constant of the living Poly-εCL−K+ ion pairs (KD 20 ≊ (4 ± 2) × 10−10 mol/L), we concluded that at the conditions indicated above and for concentrations of active centers ranging from 10−3 to 3.7 × 10−2 mol/L, propagation proceeds on the ion pairs and is disturbed neither by dissociation nor by the formation of higher aggregates. For the polymerization of εCL proceeding on the poly-εCL−K+