Engineering Phase-Segregated Graphene Nanoplatelets to Build 3D Printable, Biodegradable, and Electrically Conductive Polymer Nanocomposites 

Integration of 2D conducting materials into 3D polymer matrices increases the conductivity of polymer composites. Graphene nanoplatelets distinguish themselves through electrical conductivity (∼10⁸ S/m), non-friability, and non-toxicity. This research looked to produce a biodegradable nanocomposite material (molded and 3D-printed) that brings together high conductivity and strength through the utilization of a 3:1 polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) blend supplemented by different wt% graphene nanoplatelets (GNP H-5) mix. Calculations on interfacial energies anticipated GNP localization within PBAT. Test results by two-point probe indicated percolation thresholds at 7 wt% within moldings (~10000x increase in conductivity) and at 13 wt% within printings (~1000x), stabilizing to 1.04 S/m at 20 wt% within filaments. Results on printings were remarkable: ~1.2–1.7x higher ultimate strength and Young's modulus than moldings, and ~3x higher toughness than PLA or PP systems. Lack of an apparent correlation between GNP% and strength suggested the potential to obtain higher conductivity without sacrifice to mechanical integrity and underscores the potential of phase-separated GNP nanocomposites to serve as biodegradable flexible electronic materials.