Optimizing Epoxy Nanocomposites with Oxidized Graphene Quantum Dots for Superior Mechanical Performance: A Molecular Dynamics Approach.

Due to their excellent mechanical properties, epoxy composites are widely used in low-density applications. However, the brittle epoxy matrix often serves as the principal failure point. Matrix enhancements can be achieved by optimizing polymer combinations to maximize intermolecular interactions or by introducing fillers. While nanofillers such as clay, rubber, carbon nanotubes, and nanoplatelets enhance mechanical properties, they can lead to issues like agglomeration, voids, and poor load transfer. Quantum dots, being the smallest nanofillers, offer higher dispersion and the potential to promote intermolecular interactions, enhancing stiffness, strength, and toughness simultaneously. This study employed molecular dynamics simulations to design graphene quantum dot (GQD) reinforced epoxy nanocomposites. By functionalizing GQDs with oxygen-based groups-hydroxyl, epoxide, carboxyl, and mixed chemistries-their effects on the mechanical properties of nanocomposites were systematically evaluated. Results show that hydroxyl-functionalized GQDs provide optimal performance, increasing stiffness and yield strength by 18.4 and 56.1%, respectively. Structural analysis reveals that these GQDs promote a closely packed molecular configuration, resulting in reduced free volume.