Homogeneous Polylactic Acid (PLA)/PLA Elastomer Composites with High Strength and High Toughness Driven by Hydrogen Bonding and Structural Similarity

Polylactic acid (PLA) is a promising biodegradable alternative to petroleum-based plastics but suffers from inherent brittleness and low impact strength, severely limiting its applications in areas such as flexible electronics and automotive technology. Therefore, developing a biobased toughening agent with inherent compatibility was recognized as a key strategy to overcome this limitation without compromising the biodegradability of PLA. In this work, a PLA-derived elastomer (PLAE) with abundant hydrogen bonds (H-bonds) was introduced into PLA as a toughening agent to ensure compatibility and retain the biodegradability of composite material. Theoretical simulations in Materials Studio revealed favorable compatibility between PLA and PLAE. Consequently, PLAE was successfully blended with PLA through a simple melt-processing method without requiring any compatibilizers. The resulting composites exhibited outstanding mechanical properties, including an impact strength of 58.8 kJ/m2, tensile toughness of 94.4 MJ/m3, and high retained tensile strength of 64.2 MPa, attributed to efficient stress transfer facilitated by abundant H-bonds and good compatibility. Additionally, the composites showed excellent UV shielding efficiency (>97%) and maintained biodegradability. This work presented a scalable, biobased strategy to overcome the strength-toughness trade-off in PLA composites, offering a promising route toward sustainable flexible electronics and high-performance automotive technology.