Infusion of Graphene Quantum Dots to Create Stronger, Tougher, and Brighter Polymer Composites

Incorporation of nanoparticles into polymer resins has recently attracted a significant amount of attention from researchers for the nanoparticles' ability to alter the properties of the resin. Whereas graphene-based structures possess a two-dimensional honeycomb arrangement of carbon atoms that makes them desirable for engineering composite materials, quantum dot formulations have been primarily used in optoelectronic applications that take advantage of quantum confinement and size-tunable properties. Graphene and quantum dots (GQDs) are ubiquitous in the current research literature; however, the impact of GQD on the physical properties of polymer resins like epoxy remains unclear. Here, we show that infusing GQD into an epoxy polymer matrix results in (1) a 2.6-fold increase in the toughness of the polymer resins, (2) a 2.25-fold increase in the tensile strength of the polymer resins compared to its original tensile strength, (3) uniform loading at weight percentages as high as 10% of the polymer resin, (4) an 18% change to the max % increase in tensile strain compared to that of the neat polymer resin without GQDs, even though there is an increase in tensile strength, and (5) a 2.5-times increase in Young's modulus compared to that of the neat polymer resin, all while maintaining excellent optical properties of the composite formulation. Our results demonstrate that GQDs with dual acid and alcohol functional groups can enable high loading percentages, which, in turn, give rise to composite materials that are simultaneously stronger and tougher. We believe that these GQDs, created from an abundant source, are a starting point for new and more sophisticated composite materials with potential in mechanical, electrical, and photosensitive applications.