Soluble bimetallic μ-oxo-alkoxides. 8. Structure and kinetic behavior of the catalytic species in unsubstituted lactone ring-opening polymerization

The bimetallic µ-oxo-alkoxides are highly active for lactone ring-opening polymerization. These compounds are aggregated in solution and their mean degree of association depends on the nature of alkoxide groups, metals, and solvent; it is modified by addition of suitable ligands or temperature variations. The course of the lactone polymerization is strongly related to the structural features of the catalyst. The determination of the mean number of growing chains per catalyst molecule, the study of the polymerization kinetics, and the knowledge of the catalyst behavior during the monomer conversion have contributed to an understanding of the polymerization mechanism.