Kinetics and Mechanism of 6-caprolactone Anionic Polymerization under the Influence of Amines

The identity of the c-caprolactone products from polymerization under the influence of amines has been studied, and conclusion about alkyl oxygen fission of the lactone ring at polymerization has been made. The main kinetic features of polymerization and molecular-weight distribution change on forming poly-C-caprolactone are discussed. On the basis of these data, polymerization mechanisms for lactones under the influence of amines are proposed. INTRODUCTION In recent years lactones polymerization processes by amines have been intensively investigated. This interest is caused first of all by the fact that lactones and polylactones appear to be very effective modifiers in the cure of epoxy oligomers by amines (Refs. 1-3). It has been shown in a number of publications (Refs. 4-7) that lactones in the presence of amines can polymerize forming polyesters with reactive end groups, which is of practical interest. Unfortunately, the kinetics and mechanism of the lactones polymerization processes by amines, are not clear enough up to now and the few published results in this field are either contradictory or not correct (Refs.8&9). The review and analysis of this literature has been given (Ref. 10). The lactone ring opening by nucleophilic reagents can proceed with the fission of both acyloxygen (1) and alkyloxygen (2) (CR ) C = 0