Non-oxidative thermal degradation of poly(glycidol), poly(glycidol)-g-L- lactide, and poly(glycidol)-g-glycolide

摘要

Three polymers of pharmaceutical/medical relevance are synthesized: poly(glycidol) (PG), poly(glycidol)-g-L-lactide (PG-g-La), and poly(glycidol)-g-glycolide (PG-g-Gly). Because the thermal stability of these polymers is an essential factor of their processing and practical application, the study focuses on kinetic and mechanistic aspects of non-oxidative thermal degradation. The study is conducted by combining thermogravimetry, Fourier transform infrared spectroscopy, and isoconversional kinetic analysis. It is found that PG degrades in a single mass loss step, whereas, PG-g-La and PG-g-Gly in two. It is demonstrated that the first step in degradation of PG-g-La and PG-g-Gly is associated with decomposition of the pendant groups and the second is due to degradation of the PG backbone. Analysis of the reaction products and the kinetics of the thermal degradation of poly(glycidol) (PG) and its two derivatives, poly(glycidol)-g-L-lactide (PG-g-La) and poly(glycidol)-g-glycolide (PG-g-Gly), is performed. The results suggest that in the two-step degradation of the PG derivative, the first step is associated with decomposition of the pendant groups and the second is due to degradation of the PG backbone.