Time-of-flight secondary ion mass spectrometry studies of hydrolytic degradation kinetics at the surface of poly(glycolic acid)

This paper presents a new approach for studying the hydrolytic degradation kinetics of biodegradable polymers using time-of-flight secondary ion mass spectrometry (ToF SIMS). In this study, in vitro hydrolytic degradation of polyglycolic acid (PGA) has been carried out at 37 degrees C in aqueous sal ine buffer solutions of different pH values. The molecular weight distribut ion of hydrolysis products was obtained from the ToF SIMS spectra. The aver age molecular weight of the hydrolysis products calculated from the ToF SIM S spectra is a function of hydrolysis time. Hydrolysis kinetics equations f or PGA based on solid/liquid heterogeneous reaction conditions are establis hed. A good linear relationship was obtained using this kinetics equation. The reaction rates observed in this study generally agree with observations reported in the literature. Kinetics constants for the hydrolytic degradat ion of PGA at different pH values have been obtained. This new approach dem onstrates that ToF SIMS can be a powerful and fast technique in the study o f degradation kinetics of biodegradable polymers. Using ToF SIMS, the hydro lysis kinetics of biodegradable polymers can be explored in the range of ho urs with in-vitro methods.