Photothermal Heating of Gold Nanorods in Poly(ethyl cyanoacrylate)*

We are interested in thermally-driving chemical reactions in small volumes within a solid material, where diffusion of reactants and products is limited. Photothermal heating of nanoparticles in polymers is a potential path to better understanding and controlling polymer degradation and generating useful carbonaceous by-products. In photothermal heating, nanoparticles absorb light that enters the material and convert the energy to heat. This forms high-temperature pockets around each nanoparticle and can lead to localized chemical reactions. Poly(ethyl cyanoacrylate) (PECA) degrades by depolymerizing and in confinement the monomer will repolymerize to form oligomers. A reaction side product in this process is carbonaceous. To study this reaction, gold nanorods in PECA were photothermally heated. The resultant degradation was characterized through optical analysis of the carbonaceous by-products, which are initially luminescent, TEM analysis, and Raman spectroscopy. Outcomes from photothermal degradation are compared with those from homogeneous heating.