Syntheses of high molecular mass polyglycolides via ring‐opening polymerization with simultaneous polycondensation (ROPPOC) by means of tin and zinc catalysts

Glycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2‐ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro‐phenoxide) (BuSnOPF), zinc biscaproate (ZnCap), and zinc bis(pentafluoro‐phenyl sulfide) (ZnSPF). The temperature was varied between 110 and 180°C and the time between 3 h and 7 days. For the few polyglycolides (PGAs) that were soluble extremely high molecular masses were obtained. The MALDI TOF mass spectra had all a low signal‐to‐noise ration and displayed the peaks of cyclic PGAs with a “saw‐tooth pattern” indicating formation of extended‐ring crystallites in the mass range below m/z 2500. The shape of DSC curves varied considerably with catalyst and reaction conditions, whereas the long‐distance values measured by SAXS were small and varied little with the polymerization conditions.