In-situ Raman spectroscopy monitoring of the thermal and oxidative accelerated degradation of poly(L-lactide) (PLLA) and poly(lactide-co-glycolide) (PLGA) polymers

Abstract

The purpose of this study is to investigate the change in chemical structures of

biopolymers PLGA 80:20 and PLLA during thermal and oxidative degradation

by the means of in-situ Raman spectroscopy monitoring. Both isothermal and

non-isothermal testing, with or with little presence of oxygen, will be conducted

to monitor the changes in chemical configuration of biopolymers with respect to

the increasing degradation temperature or time. It was found that the number of

carbonyl groups and vas CH3 and vCH stretching regions decreased with

increasing degradation. The former was due to degradation of carbonyl group

while the latter was due to random chain scission. The COC regions (1092

v/cm-1, 1179 v/cm-1 and 1216 v/cm-1) were very stable throughout the whole

degradation process. Interestingly, the CCO region (398 v/cm-1 to 441 v/cm-1)

increased with prolonged degradation time. This was due to the increase in

degree of crystallinilty (DOC) of the biopolymers. This increase could be further

confirmed by the analysis done by TGA.