Core-Shell Structure Strategy to Prepare Super-tough Poly(lactic acid) Composites with Balanced Stiffness and Toughness

Abstract Super-tough poly(lactic acid) (PLA) composites with an excellent balance between stiffness and toughness were successfully developed by incorporating core-shell particles comprising a rigid silica (SiO2) core and an elastomeric poly(ether-block-amide) grafted with a glycidyl methacrylate (PEBA-GMA) shell. Morphological observations confirmed the formation of a well-defined core-shell structure within the PLA matrix. The effects of SiO2 particle size (100–800 nm) and core-shell mass ratio (1:3 to 3:1) on mechanical properties were systematically investigated. The results indicate that smaller SiO2 core particles (100 nm) led to severe agglomeration and poor dispersion, resulting in ineffective toughening. The optimal performance was achieved with PLA composites containing 500 nm SiO2 at a core-shell ratio of 1:3 and a total modifier content of 20 wt %, which exhibited a notched Izod impact strength of 70.6 kJ/m2─a significant enhancement over binary PLA/PEBA-GMA composites. Furthermore, this composite maintained ductile fracture behavior even at a high SiO2 content, with an impact strength of 33.9 kJ/m2 at a SiO2:PEBA-GMA core-shell ratio of 3:1. The flexural modulus of this optimized composite was retained at 87% of that of pure PLA, demonstrating an excellent balance between stiffness and toughness. This work presents an effective strategy for developing high-performance PLA materials with tailored mechanical properties, offering promising potential for advanced biodegradable applications.