From nutraceutics to materials: Effect of resveratrol on the stability of polylactide

Resveratrol is a naturally occurring polyphenol well known as a nutritional supplement due to its strong antioxidant properties associated with anti-inflammatory activity and possible prevention of cardiovascular diseases. In this work the effect of resveratrol on thermal thermo-oxidative and photo-oxidative degradation of polylactide is reported in the frame of developing fully biobased polymer formulations. Characterization of PLA films by thermal methods and photo-oxidative treatments demonstrated that resveratrol catalyzed high temperature transesterification reactions under inert atmosphere whereas it efficiently inhibited the exothermal oxidative reactions of the polymer backbone. Low-temperature photochemical degradation experiments on PLA films allowed elucidating the stabilization mechanisms of the phenolic additive. Resveratrol is capable of slowing the oxidative chain reaction of PLA through a peroxyl radicals scavenging mechanism while it has little effect on the direct photolytical cleavage of the ester bonds. Moreover direct resveratrol oxidation as well as the reaction between the phenol and photo-oxidized polymer species yield secondary photoproducts which are also able to protect PLA against photo-oxidation likely due to the UV screening effect of the formed chromophores. Resveratrol is thus proposed as an eco-friendly and biocompatible additive for a sustainable approach to the stabilization of PLA films in packaging a0nd other applications.