Graphene oxide induced hydrolytic degradation behavior changes of poly(l-lactide) in different mediums

Graphene oxide (GO) has been widely used in polymer-based composites due to their promising properties originated from the two-dimensional platelet-like structure and a large number of oxygen-containing groups, including reinforcement effect, nucleation effect, barrier effect, etc. In this work, GO was introduced into poly(l-lactide) (PLLA) and the main attention was focused on investigating the effect of GO on hydrolytic degradation behavior of PLLA. The hydrolytic degradation measurements were carried out in three different mediums, including alkaline solution with a pH value of 12, acidic solution with the pH value of 2 and deionized water with the pH value of 7. It was demonstrated that in all mediums, the hydrolytic degradation of PLLA was greatly accelerated by adding GO and specifically, the more the GO in the composites, the more apparent the acceleration effect of the hydrolytic degradation was, furthermore, GO didn't change the hydrolytic degradation mechanisms of the PLLA matrix in all mediums. The microstructure evolution of the PLLA matrix during the hydrolytic degradation process was also comparatively investigated. The results demonstrated that crystallization occurred during the hydrolytic degradation process and the crystallization of the composites was also greatly promoted by GO. This work provides valuable information for the application and reclamation of the PLLA/GO composites.