Cyclization and Dispersity of Polyesters

Two classes of polyesters were prepared by irreversible polycondensations. The dependence of the dispersities on the experimental parameters such as synthetic method, chemical structure, molecular weight and initial monomer concentration was determined. At first it was demonstrated that it is essential for a correct calculation of M_n and M_w to include all oligomers down to the dimers in the evaluation of SEC curves. Furthermore, it was demonstrated for poly(ϵ-caprolactone)s and polylactides that reversible polycondensations and ring-opening polymerizations with equilibration yield identical products. Finally, the dependence of the dispersity on various experimental parameters was determined for equilibrated poly(ϵ-caprolactone)s and polylactides.