Exceptional Mechanical Reinforcement of Polylactic Acid via 2D Conformal Coating of Graphene Oxide

Polylactic acid (PLA), a biodegradable, biocompatible, and environmentally friendly polymer derived from renewable resources, has gained widespread adoption in packaging, biomedical devices, and additive manufacturing. Despite its multifaceted advantages, PLA's intrinsic mechanical limitations, including low Young's modulus, poor impact resistance, and brittleness, significantly restrict its application in high-performance fields. Enhancing PLA's mechanical strength is essential to enable its deployment in demanding sectors, such as load-bearing structures and protective equipment. Graphene oxide (GO), known for its exceptional tensile strength and thermal conductivity, has emerged as a promising reinforcement material for polymer matrices. However, conventional blending methods often result in GO agglomeration and poor dispersion within the PLA matrix, limiting its effectiveness. To address these challenges, we developed a conformal coating strategy that uniformly deposits GO films onto PLA surfaces with precisely controlled layer numbers. This method ensures homogeneous coverage and alignment of GO layers, maximizing mechanical properties with minimum GO material usage. Molecular dynamics simulations predict a 4.27-fold increase in Young's modulus and a 12-fold improvement in dynamic nanoscratching resistance. Experimental nanoindentation confirms a promising modulus enhancement consistent with simulations. This scalable, cost-effective approach simplifies reinforcement, providing a universal method to enhance PLA and other polymeric materials for broad, demanding applications in structurally demanding and performance-critical environments.