Development of 3D Printing Feed Stock of Thermosets using Photothermal Refractory Plasmonic Nanomaterials.

Epoxy resin additive manufacturing is the newest trend, replacing traditional materials and techniques in various fields due to its capacity to produce complicated geometries fast and affordably. Traditionally, photoinitiators are incorporated in epoxy to enhance the curing rate using UV light. However, photo initiators can compromise the mechanical strengths of the printed parts. Additionally, microscopic voids and roughness of the surface adversely affects the printed epoxy part's mechanical integrity. Here we are developing 3-D printing feedstock by mixing thermoset polymer mixed with strongly optically absorbing photothermal refractory plasmonic titanium nitride nanomaterials. Additionally, we integrated dynamic covalent diene-dienophile links (Diels-Alder process) in epoxy to incorporate thermo-reversibility. Titanium nitride nanomaterials can efficiently, rapidly convert light into localized heating to accelerate the curing of epoxy. FTIR data suggested the curing rate with light is around 26 times faster than curing using heat when the average bulk temperature of the samples are similar. The complex viscosity of the resin significantly increases after a brief exposure to light in comparison to heat. Additionally, optical microscopy and atomic force microscopy images confirm that we could use light to controllably depolymerize targeted surface area of 3-D printed parts to smooth out the rough surface or heal any cracks.