(545g) Investigating the Effects of Photothermal Nanoparticles on Diel’s Alder Reaction Towards Development of Light Induced Recycling of Thermosets.

Thermosets are exceptionally ideal for a wide variety of applications, including adhesives, electronics, automotives, aerospace, and household gadgets, because of their remarkable mechanical qualities, strong chemical resistance, and excellent thermal stability However, the recycling of thermosets has posed a significant challenge due to their irreversible crosslinked structure limiting their reprocessability and recyclability. Furthermore, the absence of precise heating in specific areas and the low thermal conductivity of epoxies can render the recycling process utilizing bulk heating ineffective. This study involves the incorporation of refractory plasmonic Titanium Nitride (TiN) and photothermal Carbon Black (CB) nanoparticles into epoxy. These nanoparticles can absorb light and generate localized nanoscale and macroscale heat, respectively. This heat can then drive reversible reactions, such as Diels-Alder reactions, which enable the recycling of the epoxy material. Nanoparticles loading and their dispersion in the polymer matrix is optimized to maximize their photothermal efficiency. We used in situ FTIR to study the kinetics of both forward and reverse Diels Alder reactions driven by photothermal effects and compared that with conventional heat driven reaction kinetics. Moreover, the study examined the kinetics in the presence of heat using both CB and TiN and compared it to the neat Diels-Alder epoxy resin. One of our major observations is that, despite the sample having a similar bulk temperature, the forward Diels-Alder reaction kinetics with light-induced photothermal heat generation varies dramatically from conventional heating. To the contrary, the kinetics of the reverse Diels-Alder process was not significantly altered by the presence of nanoparticles and different stimuli. It implies that the Diels-Alder reactions may be impacted differently by reactant interaction with nanoparticles and local heat generation surrounding the nanoparticles. Further research is being conducted currently to understand the underlying mechanisms of photothermally induced Diels-Alder reaction.