Biomimetically Structured Poly(lactic acid)/Poly(butylene-adipate-co-terephthalate) Blends with Ultrahigh Strength and Toughness for Structural Application

The preparation of ultrastrong and super-tough polymeric materials for structural application remains a considerable challenge. To simultaneously enhance the strength and toughness of poly(lactic acid) (PLA), we successfully prepared ultrastrong and super-tough PLA/poly(butylene-adipate-co-terephthalate) (PBAT) blends by biomimetically constructing a mussel nacre-like hierarchically ordered superstructure through a simple pressure-induced flow (PIF) processing technique. The morphology, crystallization, and mechanical properties of the blends were studied. During PIF processing, the immiscible PLA/PBAT blends were forced to undergo plastic deformation, which enhanced the interaction between PBAT and PLA and resulted in the formation of an oriented nanohybrid shish-kebab-like hierarchical structure. The combination of scanning electron microscopy and two-dimensional wide-angle X-ray diffraction results demonstrated that the nanohybrid shish-kebab-like crystalline structure was formed in the blends. Due to the hierarchical structure, the PLA/PBAT (90/10) blend prepared by PIF processing at 110 °C and 100 MPa exhibited ultrahigh tensile strength (209.5 MPa), good elongation at break (91.4%), high tensile modulus (2446.7 MPa), and excellent toughness (142.6 MJ/m3), which were much higher than those prepared by an injection-molded pure PLA and PLA-based blend. According to these results, the facile, effective, and practical method employed in this study was able to fabricate high-performance polymeric materials and may be used as a viable alternative to engineering plastics for structural application.