Rigid-flexible honeycomb-like particles reinforced light-curing Poly(lactic acid) composites: Enhanced strength-toughness and cyclic reliability

Bioresorbable polymer vascular scaffolds (BRPS) show great potential for treating coronary artery disease by percutaneous coronary intervention. Poly(lactic acid) (PLA) is an ideal material for BRPS due to its excellent biocompatibility and biodegradability, whereas its inferior mechanical properties limit its application in BRPS. In this study, a novel partitioned rigid-flexible two-phase assembled honeycomb-like particles (AHPs) is designed to strengthen and toughen PLA. The influence of the fillers content on the mechanical properties of the 3D-printed PLA-based composites and associated strengthening-toughening mechanism were investigated. The results reveal 44.4% improvement in the impact strength of the PLA/2 wt%-PU&Silica AHPs composite compared to neat PLA, while the tensile strength and stiffness of the composite also improve by 11.2% and 14.1% respectively, and showing good cytocompatibility. Furthermore, in view of the long-term serviceability of BRPS in cyclic loading, the cyclic performances of the PLA and PLA/2 wt%-PU&Silica AHPs composite (i.e., cyclic stability, stress relaxation and ratchetting deformation) were also assessed. The findings show that 2 wt%-PU&Silica AHPs reinforced PLA composite exhibits cyclic stability, and that the introduction of PU&Silica AHPs can effectively suppress ratchetting deformation and stress relaxation of neat PLA. Finally, the degradation behavior of the PLA and PLA/2 wt%-PU&Silica AHPs composite were investigated through accelerated in vitro degradation tests. The results demonstrated that the PLA/2 wt%-PU&Silica AHPs exhibits a significantly slower degradation rate. The significant improvement in strength, toughness, cyclic performance, and controlled degradation behavior of the PLA-based composite makes it a highly promising candidate for BRPS.