Progress in Toughening and Functionalizing Poly(lactic acid) Composites with Two-Dimensional Layered Nanomaterials

Poly(lactic acid) (PLA), a biobased and biodegradable plastic, has garnered substantial attention due to its environmental benefits. However, the inherent brittleness, limited functionality, and challenges in balancing toughness and strength during toughening processes restrict its broader application. Recent studies have identified two-dimensional (2D) layered nanomaterials as promising reinforcing agents for improving the properties of PLA-based nanocomposites. These materials, including graphene derivatives, MXenes, layered double hydroxides (LDHs), montmorillonite (MMT), metal-organic frameworks (MOFs), and boron nitride (BN), offer unique characteristics such as atomic-level thickness, high specific surface area, and exceptional mechanical strength. This perspective provides a comprehensive overview of the progress in toughening and functionalizing PLA nanocomposites with 2D nanoscale fillers. Key preparation methods are discussed, with a focus on the dispersibility of 2D materials and their interfacial compatibility with PLA. Strategies such as surface and intercalation modifications to enhance PLA's toughness are explored in detail. The multifunctional properties imparted by 2D fillers─such as improved thermal resistance, flame retardancy, antibacterial activity, UV shielding, and barrier performance─are highlighted. Finally, this review identifies unresolved challenges and proposes future research directions to optimize the performance and applicability of PLA/2D nanocomposites for advanced applications.