Synthetic Principles Determining Local Organization of Copolyesters Prepared from Lactones and Macrolactones

A highly effective and facile technique for catalytic ring-opening copolymerization (cROP) of lactones viz. e-caprolactone and e-decalactone with ω-pentadecalactone is being described. The reactions were mediated by Zn- and Ca-based tridentate Schiff base complexes and benzyl alcohol as initiator. The catalysts were successfully employed for the preparation of numerous block and random copolymers. To unravel the composition of the polyesters, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was employed. Furthermore, the combination of solid-state NMR and XRD techniques revealed that not only the presence of branches but also intramolecular transesterification, resulting in low molecular weight cyclic structures, is responsible for a complex ordering of the polymer chain fragments. This paper focuses mainly on the detailed molecular characterization of the synthesized copolymers.