Design of an UV-C shielded biopolymer based on a poly(lactic acid)/quercetin/magnesium composite

Abstract

The use of biopolymers like poly(lactic acid) (PLA) doped with natural and harmless active agents in industrial, medical and food packaging applications is of great interest due to the multitude of property enhancements included. External factors, such as UV exposure, can accelerate the degradation process of these biomaterials and cause changes in structural and mechanical properties of medical or industrial devices. In this research, PLA-based composites with different degrees of crystallinity are fabricated using magnesium (Mg) particles and quercetin (Qr) as doping agents, providing new biomaterials with different responses against an UV-C radiation source. Physical surface changes are studied by atomic force microscopy (AFM), goniometry and scanning electron microscopy (SEM). Chemical modifications are evaluated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Thermal response is studied by differential scanning calorimetry (DSC). PLA crystallinity is crucial in the polymer response to UV radiation. Under irradiation Mg particles cause a catalytic effect that enhances the degradation by hydrolysis of PLA chains. However, when Qr is present this effect is inhibited, making the Qr/Mg combination an ideal enrichment to protect the polymer from chemical photooxidation, while improving the surface mechanical properties of the new biocomposite.