(369c) Development and Characterization of Recyclable Epoxy/Refractory Plasmonic Nanoparticles for Additive Manufacturing

Thermoset epoxy polymers are non-recyclable due to their irreversible crosslinked structure. We develop thermally reversible epoxies by incorporating dynamic covalent bonds like diene-dienophile linkages initiating Diels’ Alder reaction chemistry. However, the lack of localized heating precision and low thermal conductivity of epoxies can make the recycling using bulk heating process ineffective. We apply refractory plasmonic inexpensive Titanium Nitride (TiN) for converting the incident light to localized heat leading to depolymerization of epoxies at targeted areas. Titanium nitride nanoparticles show strong plasmonic properties due to their metallic behavior and is attractive due to their superior thermal stability and broader solar light absorption features. The incorporation of titanium nitride nanoparticles in the reversible epoxies provide several advantages: (1) application of solar light to liquefy(depolymerize) the epoxy for reprocessing, (2) targeted repair of defects on a 3-D printed epoxy structure, (3) fast curing of epoxy using light, required for their 3-D printing applications, and finally (4) smoothening the rough surface of the final products. We are functionalizing TiN nanoparticles with thiol group via sonochemical method, for better dispersion of TiN nanoparticles in the epoxy matrix. The functionalization of nanoparticles is confirmed using FTIR spectroscopy. We also characterized the nanoparticles dispersion in the composites and the surface roughness of the composite structures using Atomic Force Microscopy. The surface roughness of the structure could be reduced by 45% by melting the top surface of the structure using solar irradiation.