The hydrolytic degradation of a segmented glycolide–trimethylene carbonate copolymer (Maxon™)

Abstract

The hydrolytic degradation of a segmented copolymer constituted by glycolide and trimethylene carbonate units (Maxon™) has been investigated by means of 1H NMR spectroscopy and calorimetry. Degradation experiments have been performed either under a pH 7.4 buffered solution or in distilled water at temperatures of 37 and 50 °C. At both temperatures, the degradation proceeds through two main stages where an increase in the degree of crystallinity occurs in the first place. NMR peaks associated with glycolyl end units and appearing progressively can be well distinguished. Their chemical shifts coincide with those observed in the hydrolytic degradation of polyglycolide threads, which was also assayed for comparative purposes. Glycolide rings are also produced in a significant amount during the bulk degradation of Maxon. They are partially retained in the polymer, which may be a consequence of an intramolecular cyclization of the terminal hydroxyl groups. Thermal degradation in the presence of a transesterification catalyst has also been investigated and the changes in the polymer microstructure evaluated through the NMR analyses of signals were sensitive to the chemical sequence.