Poly(Lactic Acid)-based nanobiocomposites with modulated degradation rates

In the field of biodegradable polymers such as poly(Lactic Acid) (PLA), it is quite well known that their kinetics of hydrolysis strongly depend on the pH of the hydrolyzing medium. The idea explored during this study focused on PLA, is the addition of additives that are able to control the pH of water when it diffuses inside the polymer. For instance, acids (i.e. succinic acid, also used as food additive) are bio- and eco- friendly additives that are able to play this role. In order to control the release of these molecules and their dispersion inside the polymer, their intercalation in biocompatible nanofillers like layered double hydroxides (LDH) is here considered. The additives have been dispersed in the polymer by melt compounding, commonly used in the plastic industry. Several composites of PLA (4032D) and LDH intercalated with organic acids (succinic, fumaric, and ascorbic acid) have been obtained by an extrusion process. From all extruded materials, PLA films obtained by compression molding were then subjected to hydrolysis tests. The results showed that the mentioned molecules, dispersed in the polymer, are able to control the rate of hydrolysis, and experimental results show an increase of degradation time for samples containing LDH-organic acid (in particular with LDH-succinic acid), making such hybrid additives an appropriate and efficient solution for PLA.