Photothermally-driven oxidative degradation of LDPE nanocomposites containing plasmonic nanoparticles*

Novel approaches to control and drive polymer degradation are interesting because of the multiple challenges to remediating plastic waste including minimizing its effect when unconfined in the environment and potentially recovering value from discarded material. Photothermal heating from metal nanoparticles, where light is focused and converted into heat at the nanoscale, can be used to drive chemical reactions, such as oxidative degradation within low density polyethylene (LDPE), and results in a high temperature, high electric field environment in the particles' immediate vicinity within which reactions could be manipulated. It also provides a mechanism to convert sunlight to internal heat. We present an LDPE nanocomposite system incorporating silver nanoparticles and cobalt ions where the cobalt-mediated oxidative process is driven by heat resulting from illumination with blue light. In this configuration, the observed degradation (characterized by FTIR, absorption spectroscopy, electron microscopy and mechanical testing) under photothermal heating is almost identical to that due to heating conventionally, as expected due to the non-local oxidative process. We discuss these results and next steps.